[arch][m68k] careful of PC relative addressing on 68000 and 68010

These cpus only support a simple 16 bit offset from PC, so cannot use it in start.S to compute a large offset. This is okay, because the code that needs it is only for cpus with an MMU, which these dont have.
[arch][m68k] add arch_mmu_query so the kernel boots completely
2025-09-22 21:52:48 -07:00 · 2025-09-22 21:52:48 -07:00 · 2025-09-22 21:52:48 -07:00 · 2025-09-07 16:23:16 -07:00
17 changed files with 837 additions and 97 deletions
--- a/arch/m68k/arch.c
+++ b/arch/m68k/arch.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <arch/ops.h>
 #include <arch/m68k.h>
+#include <arch/m68k/mmu.h>
 #include <kernel/spinlock.h>

 #define LOCAL_TRACE 0
@@ -24,10 +25,16 @@ void arch_early_init(void) {
    extern uint32_t exc_vectors[256];
    asm volatile("movec %0, %%vbr" :: "r"(exc_vectors));
 #endif
+#if M68K_MMU
+    m68k_mmu_early_init();
+#endif
 }

 void arch_init(void) {
    LTRACE;
+#if M68K_MMU
+    m68k_mmu_init();
+#endif
 }

 void arch_idle(void) {
--- a/arch/m68k/exceptions.c
+++ b/arch/m68k/exceptions.c
@@ -9,6 +9,7 @@
 #include <inttypes.h>
 #include <lk/debug.h>
 #include <lk/trace.h>
+#include <assert.h>
 #include <kernel/thread.h>
 #include <target.h>

@@ -24,6 +25,27 @@ typedef struct m68k_iframe {
    uint16_t vector_offset : 12;
 } m68k_iframe_t;

+typedef struct m68k_iframe_format_7 {
+    m68k_iframe_t base;
+    uint32_t effective_address;
+    uint16_t ssw;
+    uint16_t wb3_status;
+    uint16_t wb2_status;
+    uint16_t wb1_status;
+    uint32_t fault_address;
+    uint32_t wb3_address;
+    uint32_t wb3_data;
+    uint32_t wb2_address;
+    uint32_t wb2_data;
+    uint32_t wb1_address;
+    uint32_t wb1_data;
+    uint32_t push_data_1;
+    uint32_t push_data_2;
+    uint32_t push_data_3;
+} m68k_iframe_format_7_t;
+
+static_assert(sizeof(m68k_iframe_format_7_t) - sizeof(m68k_iframe_t) == (0x3c - 0x8), "");
+
 void dump_iframe(const m68k_iframe_t *iframe) {
    printf("pc 0x%08x sr 0x%04x format %#x vector %#x\n", iframe->pc_low | iframe->pc_high << 16, iframe->sr,
            iframe->format, iframe->vector_offset / 4);
@@ -33,10 +55,28 @@ void dump_iframe(const m68k_iframe_t *iframe) {
    printf("a4 0x%08x a5 0x%08x a6 0x%08x\n", iframe->a[4], iframe->a[5], iframe->a[6]);
 }

+static void access_fault(m68k_iframe_t *frame) {
+    printf("access fault\n");
+    dump_iframe(frame);
+
+    // dump additional frame 7 stuff
+    m68k_iframe_format_7_t *f7 = (m68k_iframe_format_7_t *)frame;
+    printf("effective address %#" PRIx32 "\n", f7->effective_address);
+    printf("special status word %#" PRIx16 "\n", f7->ssw);
+    printf("halting\n");
+    for (;;);
+}
+
 void m68k_exception(m68k_iframe_t *frame) {
    uint8_t code = frame->vector_offset / 4;

-    LTRACEF("frame %p, code %#hhx\n", frame, code);
+    TRACEF("frame %p, code %#hhx\n", frame, code);
+
+    switch (code ) {
+        case 2:
+            access_fault(frame);
+            break;
+    }

    dump_iframe(frame);

--- a/arch/m68k/include/arch/aspace.h
+++ b/arch/m68k/include/arch/aspace.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2025 Travis Geiselbrecht
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+#pragma once
+
+#include <arch/m68k/mmu.h>
+
+#include <sys/types.h>
+
+struct arch_aspace {
+    /* pointer to the translation table */
+    paddr_t pgtable_phys;
+    void *pgtable_virt;
+
+    uint32_t flags;
+};
--- a/arch/m68k/include/arch/m68k/mmu.h
+++ b/arch/m68k/include/arch/m68k/mmu.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2024 Travis Geiselbrecht
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+#pragma once
+
+#if M68K_MMU
+
+void m68k_mmu_early_init(void);
+void m68k_mmu_init(void);
+
+#endif // M68K_MMU
--- a/arch/m68k/mmu.c
+++ b/arch/m68k/mmu.c
@@ -0,0 +1,467 @@
+/*
+ * Copyright (c) 2024 Travis Geiselbrecht
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+#include "arch/m68k/mmu.h"
+
+#if M68K_MMU
+
+#include <arch/mmu.h>
+#include <arch/spinlock.h>
+#include <assert.h>
+#include <kernel/vm.h>
+#include <lk/err.h>
+#include <lk/trace.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define LOCAL_TRACE 0
+
+// initial mappings set up in start.S
+struct mmu_initial_mapping mmu_initial_mappings[] = {
+    // all of memory, mapped in start.S
+    {
+        .phys = 0,
+        .virt = KERNEL_ASPACE_BASE,
+        .size = ROUNDUP(MEMSIZE, 32 * 1024 * 1024), // round up to next 32MB
+        .flags = 0,
+        .name = "physmap"},
+
+    // null entry to terminate the list
+    {}};
+
+#if M68K_MMU == 68040
+
+// 68040's layout is
+// 4 or 8K pages. only affects the bottom level
+// 32 bit entries at all levels
+//              L0,  L1,  L2
+// bits:        7,   7,   6,  12 (4K pages)
+// entries:     128, 128, 64
+// bytes/table: 512, 512, 256
+//
+// if using 4K page tables for L1 and L2, and using a small root table (L0):
+//                           L0,    L1,           L2
+// entries:                  128,   8*128 (1024), 16*64 (1024)
+// usable entries per level: 128/8, 1024/16,      1024
+
+// 68040 L2 table entry
+typedef struct pte {
+    uint32_t page_address : 20;
+    uint32_t ur : 1;
+    uint32_t g : 1;
+    uint32_t u1 : 1;
+    uint32_t u0 : 1;
+    uint32_t s : 1;
+    uint32_t cm : 2;
+    uint32_t m : 1;
+    uint32_t u : 1;
+    uint32_t w : 1;
+    uint32_t pdt : 2;
+} pte_t;
+static_assert(sizeof(pte_t) == 4, "");
+
+// 68040 L1 table entry
+typedef struct ptp {
+    uint32_t table_address : 24;
+    uint32_t _1 : 4;
+    uint32_t u : 1;
+    uint32_t w : 1;
+    uint32_t udt : 2;
+} ptp_t;
+static_assert(sizeof(ptp_t) == 4, "");
+
+// 68040 L0 table entry
+typedef struct root_ptp {
+    uint32_t table_address : 23;
+    uint32_t _1 : 5;
+    uint32_t u : 1;
+    uint32_t w : 1;
+    uint32_t udt : 2;
+} root_ptp_t;
+static_assert(sizeof(root_ptp_t) == 4, "");
+
+// some constants based on this
+#define L0_SHIFT_RAW 7
+#define L1_SHIFT_RAW 7
+#define L2_SHIFT_RAW 6
+
+// number of entries to repeat per level to get our emulated tables
+#define L0_REPEAT_SHIFT 3
+#define L1_REPEAT_SHIFT 4
+
+#define L0_REPEATS (1 << L0_REPEAT_SHIFT)
+#define L1_REPEATS (1 << L1_REPEAT_SHIFT)
+static_assert(L0_REPEATS == 8, "");
+static_assert(L1_REPEATS == 16, "");
+
+// number of entries per level
+#define L0_ENTRIES_RAW (1 << L0_SHIFT_RAW)
+#define L1_ENTRIES_RAW (1 << (L1_SHIFT_RAW + L0_REPEAT_SHIFT))
+#define L2_ENTRIES_RAW (1 << (L2_SHIFT_RAW + L1_REPEAT_SHIFT))
+static_assert(L0_ENTRIES_RAW == 128, "");
+static_assert(L1_ENTRIES_RAW == 1024, "");
+static_assert(L2_ENTRIES_RAW == 1024, "");
+
+// number of bytes per level
+#define L0_BYTES (L0_ENTRIES_RAW * sizeof(root_ptp_t))
+#define L1_BYTES (L1_ENTRIES_RAW * sizeof(ptp_t))
+#define L2_BYTES (L2_ENTRIES_RAW * sizeof(pte_t))
+static_assert(L0_BYTES == 512, "");
+static_assert(L1_BYTES == 4096, "");
+static_assert(L2_BYTES == 4096, "");
+
+// number of unique entries per level
+// pow2 4+6+10
+#define L0_ENTRIES (1u << (L0_SHIFT_RAW - L0_REPEAT_SHIFT))
+#define L1_ENTRIES (1u << (L1_SHIFT_RAW - L1_REPEAT_SHIFT + L0_REPEAT_SHIFT))
+#define L2_ENTRIES (1u << (L2_SHIFT_RAW + L1_REPEAT_SHIFT))
+static_assert(L0_ENTRIES == 16, "");
+static_assert(L1_ENTRIES == 64, "");
+static_assert(L2_ENTRIES == 1024, "");
+
+// for a given virtual address, which bits correspond to what layer of the table
+#define L0_VADDR_SHIFT (32 - L0_SHIFT_RAW)
+#define L1_VADDR_SHIFT (L0_VADDR_SHIFT - L1_SHIFT_RAW)
+#define L2_VADDR_SHIFT (L1_VADDR_SHIFT - L2_SHIFT_RAW)
+
+static_assert(L0_VADDR_SHIFT == 25, "");
+static_assert(L1_VADDR_SHIFT == 18, "");
+static_assert(L2_VADDR_SHIFT == 12, "");
+
+static volatile root_ptp_t kernel_pgtable[L0_ENTRIES_RAW] __ALIGNED(L0_BYTES);
+
+#else
+// TODO: support 65030 in the future, probably using identical page table sizes
+#error "unsupported m68k mmu"
+#endif
+
+static status_t alloc_pgtable(paddr_t *paddrp) {
+#if WITH_KERNEL_VM
+    vm_page_t *p = pmm_alloc_page();
+    if (!p) {
+        return ERR_NO_MEMORY;
+    }
+    *paddrp = vm_page_to_paddr(p);
+#else
+    // XXX hack for now before we allocate from PMM
+    static uint32_t pgtables[L0_ENTRIES * L1_ENTRIES * L2_ENTRIES] __ALIGNED(PAGE_SIZE);
+    static size_t next_pgtable = 0;
+    *paddrp = (paddr_t)&pgtables[next_pgtable * L2_ENTRIES];
+    next_pgtable++;
+    LTRACEF("returning %#lx\n", *paddrp);
+#endif
+    return NO_ERROR;
+}
+
+// given a vaddr, generate the virtual index of the page table at that level.
+// Needs to be shifted by Ln_REPEAT_SHIFT to get the raw entry
+static uint get_l0_index(vaddr_t vaddr) {
+    return (vaddr >> (L0_VADDR_SHIFT + L0_REPEAT_SHIFT)) & (L0_ENTRIES - 1);
+}
+
+static uint get_l1_index(vaddr_t vaddr) {
+    return (vaddr >> (L1_VADDR_SHIFT + L1_REPEAT_SHIFT)) & (L1_ENTRIES - 1);
+}
+
+static uint get_l2_index(vaddr_t vaddr) {
+    return (vaddr >> L2_VADDR_SHIFT) & (L2_ENTRIES - 1);
+}
+
+// Return a pointer to the first, possibly repeated, page table pointer in this level.
+// Any updates will need to be repeated L0_REPEATS
+static volatile root_ptp_t *get_l0_ptp_base_ptr(volatile root_ptp_t *table, vaddr_t vaddr) {
+    const unsigned int idx = get_l0_index(vaddr) << L0_REPEAT_SHIFT;
+    LTRACEF_LEVEL(3, "vaddr %#lx shifted idx: %u\n", vaddr, idx);
+
+    return &table[idx];
+}
+
+// Return a pointer to the first, possibly repeated, page table pointer in this level.
+// Any updates will need to be repeated L1_REPEATS
+static volatile ptp_t *get_l1_ptp_base_ptr(volatile ptp_t *table, vaddr_t vaddr) {
+    const unsigned int idx = get_l1_index(vaddr) << L1_REPEAT_SHIFT;
+    LTRACEF_LEVEL(3, "vaddr %#lx shifted idx: %u\n", vaddr, idx);
+
+    return &table[idx];
+}
+
+__NO_INLINE static void map_l0(volatile root_ptp_t *root_table, vaddr_t vaddr, paddr_t paddr) {
+    LTRACEF("vaddr %#lx paddr %#lx\n", vaddr, paddr);
+
+    volatile root_ptp_t *entry = get_l0_ptp_base_ptr(root_table, vaddr);
+    for (uint i = 0; i < L0_REPEATS; i++) {
+        const paddr_t pa = paddr + i * (1u << L1_SHIFT_RAW) * sizeof(ptp_t);
+
+        const root_ptp_t ptp = {
+            .table_address = pa >> 9,
+            .u = 0,   // not used
+            .w = 0,   // not write protected
+            .udt = 3, // resident
+        };
+        entry[i] = ptp;
+        LTRACEF_LEVEL(2, "real addr: %lx, index %u, shifted index %u\n", pa, get_l0_index(vaddr), (get_l0_index(vaddr) << L0_REPEAT_SHIFT) + i);
+    }
+}
+
+__NO_INLINE static void map_l1(volatile ptp_t *table, vaddr_t vaddr, paddr_t paddr) {
+    LTRACEF("vaddr %#lx paddr %#lx\n", vaddr, paddr);
+
+    volatile ptp_t *entry = get_l1_ptp_base_ptr(table, vaddr);
+    for (unsigned int i = 0; i < L1_REPEATS; i++) {
+        const paddr_t pa = paddr + i * (1u << L2_SHIFT_RAW) * sizeof(ptp_t);
+
+        const ptp_t ptp = {
+            .table_address = pa >> 8,
+            .u = 0,   // not used
+            .w = 0,   // not write protected
+            .udt = 3, // resident
+        };
+        entry[i] = ptp;
+        LTRACEF_LEVEL(2, "real addr: %lx, index %u, shifted index %u\n", pa, get_l1_index(vaddr), (get_l1_index(vaddr) << L1_REPEAT_SHIFT) + i);
+    }
+}
+
+__NO_INLINE static void map_l2(volatile pte_t *table, vaddr_t vaddr, paddr_t addr) {
+    const unsigned int idx = get_l2_index(vaddr);
+    LTRACEF_LEVEL(2, "vaddr %#lx paddr %#lx, shifted idx: %u\n", vaddr, addr, idx);
+
+    DEBUG_ASSERT(idx < L2_ENTRIES);
+
+    const pte_t pte = {
+        .page_address = addr >> 12,
+        .g = 0,   // not global
+        .s = 1,   // supervisor
+        .cm = 0,  // cache mode, cacheable
+        .m = 0,   // not modified
+        .u = 0,   // not used
+        .w = 0,   // not write protected
+        .pdt = 1, // resident
+    };
+    table[idx] = pte;
+}
+
+#define MMU_REG_ACCESSOR(reg)                                       \
+    static uint32_t get_##reg(void) {                               \
+        uint32_t reg;                                               \
+        asm volatile("movec %%" #reg ", %0" : "=r"(reg)::"memory"); \
+        return reg;                                                 \
+    }                                                               \
+    static void set_##reg(uint32_t val) {                           \
+        asm volatile("movec %0, %%" #reg ::"r"(val) : "memory");    \
+    }
+
+// Control register accessors
+MMU_REG_ACCESSOR(tc);
+MMU_REG_ACCESSOR(itt0);
+MMU_REG_ACCESSOR(itt1);
+MMU_REG_ACCESSOR(dtt0);
+MMU_REG_ACCESSOR(dtt1);
+MMU_REG_ACCESSOR(mmusr);
+MMU_REG_ACCESSOR(urp);
+MMU_REG_ACCESSOR(srp);
+
+static void dump_mmu_regs(void) {
+    // Dump all the registers
+    printf("TC %#x\n", get_tc());
+    printf("ITT0 %#x\n", get_itt0());
+    printf("ITT1 %#x\n", get_itt1());
+    printf("DTT0 %#x\n", get_dtt0());
+    printf("DTT1 %#x\n", get_dtt1());
+    printf("MMUSR %#x\n", get_mmusr());
+    printf("URP %#x\n", get_urp());
+    printf("SRP %#x\n", get_srp());
+}
+
+static bool is_l0_entry_valid(root_ptp_t entry) {
+    // 0, 1 == invalid
+    // 2, 3 == valid
+    return entry.udt > 2;
+}
+
+static bool is_l1_entry_valid(ptp_t entry) {
+    // 0, 1 == invalid
+    // 2, 3 == valid
+    return entry.udt > 2;
+}
+
+static bool is_l2_entry_valid(pte_t entry) {
+    // 0 == invalid
+    // 1, 2 == valid
+    // 3 == indirect pointer (unused)
+    return entry.pdt == 1 || entry.pdt == 2;
+}
+
+void m68k_mmu_early_init(void) {}
+
+static status_t map_range(vaddr_t va, paddr_t pa, size_t len_minus_one) {
+    DEBUG_ASSERT(IS_ALIGNED(va, PAGE_SIZE));
+    DEBUG_ASSERT(IS_ALIGNED(pa, PAGE_SIZE));
+    DEBUG_ASSERT(IS_ALIGNED(len_minus_one + 1, PAGE_SIZE));
+
+    const vaddr_t terminal_va = va + len_minus_one + 1;
+
+    // iterate over the L0 level
+    for (;;) {
+        const root_ptp_t l0_entry = *get_l0_ptp_base_ptr(kernel_pgtable, va);
+        volatile ptp_t *l1_pgtable;
+        if (!is_l0_entry_valid(l0_entry)) {
+            // allocate a page table
+            paddr_t pgtable;
+            status_t err = alloc_pgtable(&pgtable);
+            if (err < 0) {
+                TRACEF("error allocating L1 page table\n");
+                return err;
+            }
+            map_l0(kernel_pgtable, va, pgtable);
+            l1_pgtable = (volatile ptp_t *)pgtable;
+        } else {
+            l1_pgtable = (volatile ptp_t *)((uintptr_t)l0_entry.table_address << 9);
+        }
+
+        // iterate over the L1 level
+        do {
+            const ptp_t l1_entry = *get_l1_ptp_base_ptr(l1_pgtable, va);
+            volatile pte_t *l2_pgtable;
+            if (!is_l1_entry_valid(l1_entry)) {
+                // allocate a page table
+                paddr_t pgtable;
+                status_t err = alloc_pgtable(&pgtable);
+                if (err < 0) {
+                    TRACEF("error allocating L2 page table\n");
+                    return err;
+                }
+                map_l1(l1_pgtable, va, pgtable);
+                l2_pgtable = (volatile pte_t *)pgtable;
+            } else {
+                l2_pgtable = (volatile pte_t *)((uintptr_t)l1_entry.table_address << 8);
+            }
+
+            // for every L2 page table entry, map a page
+            do {
+                map_l2(l2_pgtable, va, pa);
+                va += PAGE_SIZE;
+                pa += PAGE_SIZE;
+
+                // If we hit the terminal address, stop
+                if (va == terminal_va) {
+                    return NO_ERROR;
+                }
+            } while (get_l2_index(va) != 0);
+        } while (get_l1_index(va) != 0);
+    }
+    return NO_ERROR;
+}
+
+void m68k_mmu_init(void) {
+    LTRACE_ENTRY;
+
+#if 0
+    // set up some helpful maps for qemu virt
+    map_range(0, 0, 64 * 1024 * 1024 - 1);
+    map_range(0xff000000, 0xff000000, 0 - 0xff000000 - 1);
+
+    // a few test mappings to stress the mapper
+    map_range(0xc0104000, 0x12345000, 0x268000 - 1);
+    map_range(0xc0371000, 0x6789a000, 0x440000 - 1);
+
+    // set the root pointers
+    set_srp((uint32_t)(uintptr_t)kernel_pgtable);
+    set_urp((uint32_t)(uintptr_t)kernel_pgtable);
+    set_tc((1 << 15)); // enable, 4K pages
+#endif
+
+    dump_mmu_regs();
+
+    LTRACE_EXIT;
+}
+
+// Default stub implementations for arch_mmu routines
+
+bool arch_mmu_supports_nx_mappings(void) {
+    return false;
+}
+
+bool arch_mmu_supports_ns_mappings(void) {
+    return false;
+}
+
+bool arch_mmu_supports_user_aspaces(void) {
+    return false;
+}
+
+status_t arch_mmu_init_aspace(arch_aspace_t *aspace, vaddr_t base, size_t size, uint flags) {
+    return ERR_NOT_SUPPORTED;
+}
+
+status_t arch_mmu_destroy_aspace(arch_aspace_t *aspace) {
+    return ERR_NOT_SUPPORTED;
+}
+
+int arch_mmu_map(arch_aspace_t *aspace, vaddr_t vaddr, paddr_t paddr, uint count, uint flags) {
+    return ERR_NOT_SUPPORTED;
+}
+
+int arch_mmu_unmap(arch_aspace_t *aspace, vaddr_t vaddr, uint count) {
+    return ERR_NOT_SUPPORTED;
+}
+
+status_t arch_mmu_query(arch_aspace_t *aspace, vaddr_t vaddr, paddr_t *paddr, uint *flags) {
+    // Disable interrupts around the ptest instruction in case we get preempted
+    spin_lock_saved_state_t state;
+    arch_interrupt_save(&state, 0);
+
+    // Use the PTEST instruction to probe the translation
+    uint32_t mmusr;
+    asm volatile(
+        "ptestr (%1)\n"
+        "movec %%mmusr, %0"
+        : "=r"(mmusr) : "a"(vaddr) : "memory");
+
+    arch_interrupt_restore(state, 0);
+
+    LTRACEF("vaddr %#x, mmusr %#x\n", (uint32_t)vaddr, mmusr);
+    if ((mmusr & 0x1) == 0) {
+        return ERR_NOT_FOUND;
+    }
+
+    // extract the physical address from the mmusr
+    if (paddr) {
+        *paddr = (mmusr & 0xfffff000) | (vaddr & 0xfff);
+    }
+    if (flags) {
+        *flags = 0;
+        *flags |= (mmusr & (1 << 2)) ? ARCH_MMU_FLAG_PERM_RO : 0;
+        *flags |= (mmusr & (1 << 7)) ? 0 : ARCH_MMU_FLAG_PERM_USER;
+        uint32_t cm = mmusr & (3 << 5);
+        switch (cm) {
+            case 0:
+            case 1:
+                *flags |= ARCH_MMU_FLAG_CACHED;
+                break;
+            case 2:
+                *flags |= ARCH_MMU_FLAG_UNCACHED_DEVICE;
+                break;
+            case 3:
+                *flags |= ARCH_MMU_FLAG_UNCACHED;
+                break;
+        }
+    }
+    return NO_ERROR;
+}
+
+vaddr_t arch_mmu_pick_spot(arch_aspace_t *aspace,
+                           vaddr_t base, uint prev_region_arch_mmu_flags,
+                           vaddr_t end, uint next_region_arch_mmu_flags,
+                           vaddr_t align, size_t size, uint arch_mmu_flags) {
+    return (vaddr_t)NULL;
+}
+
+void arch_mmu_context_switch(arch_aspace_t *aspace) {
+    // no-op
+}
+
+#endif // M68K_MMU
--- a/arch/m68k/rules.mk
+++ b/arch/m68k/rules.mk
@@ -6,6 +6,7 @@ MODULE_SRCS += $(LOCAL_DIR)/arch.c
 MODULE_SRCS += $(LOCAL_DIR)/asm.S
 MODULE_SRCS += $(LOCAL_DIR)/exceptions.c
 MODULE_SRCS += $(LOCAL_DIR)/exceptions_asm.S
+MODULE_SRCS += $(LOCAL_DIR)/mmu.c
 MODULE_SRCS += $(LOCAL_DIR)/start.S
 MODULE_SRCS += $(LOCAL_DIR)/thread.c

@@ -27,8 +28,10 @@ else ifeq ($(M68K_CPU),68020)
 ARCH_COMPILEFLAGS := -mcpu=68020
 else ifeq ($(M68K_CPU),68030)
 ARCH_COMPILEFLAGS := -mcpu=68030
+M68K_MMU := 68030
 else ifeq ($(M68K_CPU),68040)
 ARCH_COMPILEFLAGS := -mcpu=68040
+M68K_MMU := 68040
 else
 $(error add support for selected cpu $(M68K_CPU))
 endif
@@ -39,13 +42,38 @@ $(info LIBGCC = $(LIBGCC))
 cc-option = $(shell if test -z "`$(1) $(2) -S -o /dev/null -xc /dev/null 2>&1`"; \
 	then echo "$(2)"; else echo "$(3)"; fi ;)

-ARCH_OPTFLAGS := -O2
+# default to no mmu
+WITH_MMU ?= 0

+ifeq (true, $(call TOBOOL, $(WITH_MMU)))
+ifeq ($(M68K_MMU),)
+$(error WITH_MMU is set but no M68K_MMU is set)
+endif
+# we have a mmu and want the vmm/pmm
+WITH_KERNEL_VM := 1
+
+GLOBAL_DEFINES += ARCH_HAS_MMU=1
+GLOBAL_DEFINES += M68K_MMU=$(M68K_MMU)
+
+# Have the kernel occupy the top 2GB of the address space.
+# This puts the kernel at 0x8000.0000
+GLOBAL_DEFINES += \
+    KERNEL_ASPACE_BASE=0x80000000 \
+    KERNEL_ASPACE_SIZE=0x80000000
+
+KERNEL_BASE ?= 0x80000000
+KERNEL_LOAD_OFFSET ?= 0
+else
 KERNEL_BASE ?= $(MEMBASE)
 KERNEL_LOAD_OFFSET ?= 0
+endif
+
+ARCH_OPTFLAGS := -O2

 GLOBAL_DEFINES += MEMBASE=$(MEMBASE)
 GLOBAL_DEFINES += MEMSIZE=$(MEMSIZE)
+GLOBAL_DEFINES += KERNEL_BASE=$(KERNEL_BASE)
+GLOBAL_DEFINES += KERNEL_LOAD_OFFSET=$(KERNEL_LOAD_OFFSET)
 GLOBAL_DEFINES += M68K_CPU=$(M68K_CPU)
 GLOBAL_DEFINES += M68K_CPU_$(M68K_CPU)=1

--- a/arch/m68k/start.S
+++ b/arch/m68k/start.S
@@ -11,10 +11,10 @@
 FUNCTION(_start)
    // load the first 4 args that were pushed on whatever stack we have
    // NOTE: assumes stack is pointing at at least readable memory
-    movl    %sp@(4),%d0
-    movl    %sp@(8),%d1
-    movl    %sp@(12),%d2
-    movl    %sp@(16),%d3
+    movl    %sp@(4),%d4
+    movl    %sp@(8),%d5
+    movl    %sp@(12),%d6
+    movl    %sp@(16),%d7

 #if ARCH_DO_RELOCATION
    lea     %pc@(_start),%a0 // load the current address using PC relative addressing mode
@@ -39,8 +39,18 @@ FUNCTION(_start)

    // clear bss
 bss_clear:
-    lea     __bss_start,%a0
-    lea     __bss_end,%a1
+#if M68K_CPU >= 68020
+    // 020 and above have a full 32bit PC relative addressing mode.
+    // Since we may be using a mmu in this case, we may be operating in physical address space,
+    // so we need to use PC relative addressing to get the right addresses.
+    lea     %pc@(__bss_start),%a0
+    lea     %pc@(__bss_end),%a1
+#else
+    // We wont be using an MMU on 68000 and 68010, so we can use absolute addresses.
+    movl     __bss_start,%a0
+    movl     __bss_end,%a1
+#endif
+
    cmpl    %a0,%a1
    beqs    1f
    // zero 4 bytes at a time
@@ -50,14 +60,81 @@ bss_clear:
    bne     0b
 1:

+#if M68K_MMU == 68040
+init_mmu_68040:
+    // Set up DTTR0 and ITTR0 to map 0x00000000 - 0x3FFFFFFF (1GB) to 0x00000000
+    // Logical address base: 0x00000000, mask 0x3f000000, enable, supervisor, cacheble, copyback
+    movl    #0x003fa020,%d0
+    movec   %d0,%dtt0
+    movec   %d0,%itt0
+
+    // Set up an mapping of [0, MEMSIZE) to [KERNEL_ASPACE_BASE, KERNEL_ASPACE_BASE + MEMSIZE)
+
+    // Set up L0 entries
+    lea    %pc@(_root_page_table),%a0
+    addl   #(KERNEL_ASPACE_BASE / L0_ENTRY_RANGE * 4),%a0    // offset into the middle of the L0 table for KERNEL_ASPACE_BASE
+    movl   #L0_ENTRIES,%d0
+    lea    %pc@(_l1_tables),%a1   // get pointer to L1 tables
+    addl   #0x00000003,%a1        // mark it valid
+.Ll0_loop:
+    movl   %a1,%a0@               // store it in the L0 table
+    addl   #4,%a0                 // advance to next L0 entry
+    addl   #L1_PGTABLE_ENTRIES * 4,%a1 // advance to next L1 table
+    subl   #1,%d0
+    bne    .Ll0_loop
+
+    // Set up L1 entries
+    lea    %pc@(_l1_tables),%a0
+    movl   #L1_ENTRIES,%d0
+    lea    %pc@(_l2_tables),%a1   // get pointer to L2 table
+    addl   #0x00000003,%a1        // mark it valid
+
+.Ll1_loop:
+    movl   %a1,%a0@
+    addl   #4,%a0
+    addl   #L2_PGTABLE_ENTRIES * 4,%a1 // advance to next L1 table
+    subl   #1,%d0
+    bne    .Ll1_loop
+
+    // Set up L2 entries
+    lea    %pc@(_l2_tables),%a0
+    movl   #L2_ENTRIES,%d0
+    movl   #0x000000083,%d1       // address 0, supervisor, writable, present
+.L2_loop:
+    movl   %d1,%a0@               // read the current entry
+    addl   #4,%a0                 // advance to next L2 entry
+    addl   #PAGE_SIZE,%d1         // advance to next page
+    subl   #1,%d0
+    bne    .L2_loop
+
+    // set the supervisor root pointer
+    lea    %pc@(_root_page_table),%a0
+    movec  %a0,%srp
+    movec  %a0,%urp
+
+    // enable the mmu
+    movl   #(1<<15),%d0
+    movec  %d0,%tc
+
+    // Branch to the high memory area
+    movl   #.Lhigh_target,%a0
+    jmp     %a0@
+.Lhigh_target:
+
+    // Turn off DTTR0 and ITTR0
+    clrl    %d0
+    movec   %d0,%dtt0
+    movec   %d0,%itt0
+#endif
+
    // load the initial stack pointer
    lea     _default_stack_top,%sp

    // branch into C land with 4 args off the previous stack
-    movl    %d3,%sp@-
-    movl    %d2,%sp@-
-    movl    %d1,%sp@-
-    movl    %d0,%sp@-
+    movl    %d7,%sp@-
+    movl    %d6,%sp@-
+    movl    %d5,%sp@-
+    movl    %d4,%sp@-
    jsr     lk_main

    // if we return from main just loop forever
@@ -65,8 +142,35 @@ bss_clear:
 END_FUNCTION(_start)

 .bss
-.align 4
+.balign 4
 _default_stack_base:
    .skip 4096
 _default_stack_top:

+#if M68K_MMU == 68040
+// Define space for page tables to set up a mapping of MEMSIZE bytes of memory at KERNEL_ASPACE_BASE
+.equ PAGE_SIZE, 4096
+.equ L0_PGTABLE_ENTRIES, 128 // 7 bits
+.equ L0_ENTRY_RANGE, (1<<25) // each L0 entry covers 32MB
+.equ L1_PGTABLE_ENTRIES, 128 // 7 bits
+.equ L1_ENTRY_RANGE, (1<<18) // each L1 entry covers 256KB
+.equ L2_PGTABLE_ENTRIES, 64  // 6 bits
+
+// Number of entries at each level to fill in order to cover MEMSIZE,
+// rounded up to the next L0 entry range so all of the L1 and L2 page tables are fully used.
+.equ MEMSIZE_ROUNDED, (MEMSIZE + L0_ENTRY_RANGE - 1) & ~(L0_ENTRY_RANGE - 1)
+.equ L0_ENTRIES, MEMSIZE_ROUNDED / L0_ENTRY_RANGE
+.equ L1_ENTRIES, MEMSIZE_ROUNDED / L1_ENTRY_RANGE
+.equ L2_ENTRIES, MEMSIZE_ROUNDED / PAGE_SIZE
+
+.balign 4096
+_root_page_table:
+    .skip L0_PGTABLE_ENTRIES * 4 // 128 entries, 4 bytes each
+.balign 4096
+_l1_tables:
+    .skip L1_ENTRIES * 4 // 4 bytes each, one per 256KB section of memory
+.balign 4096
+_l2_tables:
+    .skip L2_ENTRIES * 4 // 4 bytes each, one per page of memory
+
+#endif // M68K_MMU == 68040
--- a/platform/qemu-virt-m68k/bootinfo.c
+++ b/platform/qemu-virt-m68k/bootinfo.c
@@ -8,8 +8,8 @@
 #include "bootinfo.h"

 #include <lk/compiler.h>
-#include <lk/trace.h>
 #include <lk/debug.h>
+#include <lk/trace.h>
 #include <stdio.h>

 #define LOCAL_TRACE 0
@@ -18,22 +18,38 @@ extern uint8_t __bss_end;

 static const char *bootinfo_tag_to_string(enum BOOTINFO_TAGS tag) {
    switch (tag) {
-        case BOOTINFO_TAG_END: return "END";
-        case BOOTINFO_TAG_MACHTYPE: return "MACHTYPE";
-        case BOOTINFO_TAG_CPUTYPE: return "CPUTYPE";
-        case BOOTINFO_TAG_FPUTYPE: return "FPUTYPE";
-        case BOOTINFO_TAG_MMUTYPE: return "MMUTYPE";
-        case BOOTINFO_TAG_MEMCHUNK: return "MEMCHUNK";
-        case BOOTINFO_TAG_RAMDISK: return "RAMDISK";
-        case BOOTINFO_TAG_COMMAND_LINE: return "COMMAND_LINE";
-        case BOOTINFO_TAG_RNG_SEED: return "RNG_SEED";
-        case BOOTINFO_TAG_VIRT_QEMU_VERSION: return "VIRT_QEMU_VERSION";
-        case BOOTINFO_TAG_VIRT_GF_PIC_BASE: return "VIRT_GF_PIC_BASE";
-        case BOOTINFO_TAG_VIRT_GF_RTC_BASE: return "VIRT_GF_RTC_BASE";
-        case BOOTINFO_TAG_VIRT_GF_TTY_BASE: return "VIRT_GF_TTY_BASE";
-        case BOOTINFO_TAG_VIRT_VIRTIO_BASE: return "VIRT_VIRTIO_BASE";
-        case BOOTINFO_TAG_VIRT_CTRL_BASE: return "VIRT_CTRL_BASE";
-        default: return "UNKNOWN";
+        case BOOTINFO_TAG_END:
+            return "END";
+        case BOOTINFO_TAG_MACHTYPE:
+            return "MACHTYPE";
+        case BOOTINFO_TAG_CPUTYPE:
+            return "CPUTYPE";
+        case BOOTINFO_TAG_FPUTYPE:
+            return "FPUTYPE";
+        case BOOTINFO_TAG_MMUTYPE:
+            return "MMUTYPE";
+        case BOOTINFO_TAG_MEMCHUNK:
+            return "MEMCHUNK";
+        case BOOTINFO_TAG_RAMDISK:
+            return "RAMDISK";
+        case BOOTINFO_TAG_COMMAND_LINE:
+            return "COMMAND_LINE";
+        case BOOTINFO_TAG_RNG_SEED:
+            return "RNG_SEED";
+        case BOOTINFO_TAG_VIRT_QEMU_VERSION:
+            return "VIRT_QEMU_VERSION";
+        case BOOTINFO_TAG_VIRT_GF_PIC_BASE:
+            return "VIRT_GF_PIC_BASE";
+        case BOOTINFO_TAG_VIRT_GF_RTC_BASE:
+            return "VIRT_GF_RTC_BASE";
+        case BOOTINFO_TAG_VIRT_GF_TTY_BASE:
+            return "VIRT_GF_TTY_BASE";
+        case BOOTINFO_TAG_VIRT_VIRTIO_BASE:
+            return "VIRT_VIRTIO_BASE";
+        case BOOTINFO_TAG_VIRT_CTRL_BASE:
+            return "VIRT_CTRL_BASE";
+        default:
+            return "UNKNOWN";
    }
 }

@@ -88,4 +104,3 @@ const void *bootinfo_find_record(uint16_t id, uint16_t *size_out) {
        ptr += item->size;
    }
 }
-
--- a/platform/qemu-virt-m68k/goldfish_rtc.c
+++ b/platform/qemu-virt-m68k/goldfish_rtc.c
@@ -7,24 +7,22 @@
 */
 #include "platform_p.h"

-#include <assert.h>
-#include <inttypes.h>
-#include <lk/err.h>
-#include <lk/debug.h>
-#include <lk/reg.h>
-#include <lk/trace.h>
 #include <kernel/debug.h>
 #include <kernel/thread.h>
-#include <platform/interrupts.h>
-#include <platform/virt.h>
-#include <platform/timer.h>
+#include <lk/debug.h>
+#include <lk/err.h>
+#include <lk/reg.h>
+#include <lk/trace.h>
 #include <platform.h>
+#include <platform/interrupts.h>
+#include <platform/timer.h>
+#include <platform/virt.h>

 #define LOCAL_TRACE 0

 // implementation of RTC at
 // https://github.com/qemu/qemu/blob/master/hw/rtc/goldfish_rtc.c
-volatile uint32_t * const goldfish_rtc_base = (void *)VIRT_GF_RTC_MMIO_BASE;
+volatile uint32_t *const goldfish_rtc_base = (void *)VIRT_GF_RTC_MMIO_BASE;

 // registers
 enum {
@@ -105,7 +103,7 @@ lk_time_t current_time(void) {
    return (lk_time_t)(t / 1000000ULL); // ns -> ms
 }

-status_t platform_set_oneshot_timer (platform_timer_callback callback, void *arg, lk_time_t interval) {
+status_t platform_set_oneshot_timer(platform_timer_callback callback, void *arg, lk_time_t interval) {
    LTRACEF("callback %p, arg %p, interval %u\n", callback, arg, interval);

    t_callback = callback;
@@ -126,5 +124,3 @@ void platform_stop_timer(void) {
    write_reg(RTC_CLEAR_ALARM, 1);
    write_reg(RTC_CLEAR_INTERRUPT, 1);
 }
-
-
--- a/platform/qemu-virt-m68k/goldfish_tty.c
+++ b/platform/qemu-virt-m68k/goldfish_tty.c
@@ -5,21 +5,25 @@
 * license that can be found in the LICENSE file or at
 * https://opensource.org/licenses/MIT
 */
+#include <kernel/thread.h>
+#include <lib/cbuf.h>
 #include <lk/reg.h>
 #include <lk/trace.h>
-#include <lib/cbuf.h>
-#include <kernel/thread.h>
 #include <platform.h>
-#include <platform/interrupts.h>
 #include <platform/debug.h>
+#include <platform/interrupts.h>
 #include <platform/virt.h>
 #include <sys/types.h>

+#if WITH_KERNEL_VM
+#include <kernel/vm.h>
+#endif
+
 #include "platform_p.h"

 // goldfish tty
 // from https://github.com/qemu/qemu/blob/master/hw/char/goldfish_tty.c
-volatile uint32_t * const goldfish_tty_base = (void *)VIRT_GF_TTY_MMIO_BASE;
+volatile uint32_t *const goldfish_tty_base = (void *)VIRT_GF_TTY_MMIO_BASE;

 // registers
 enum {
@@ -59,7 +63,8 @@ static enum handler_return uart_irq_handler(void *arg) {
    bool resched = false;

    // use a DMA read of one byte if a byte is ready
-    if (read_reg(REG_BYTES_READY) > 0) {
+    uint32_t ready = read_reg(REG_BYTES_READY);
+    if (ready > 0) {
        write_reg(REG_CMD, CMD_READ_BUFFER);
        char c = transfer_buf[0];
        cbuf_write_char(&uart_rx_buf, c, false);
@@ -74,7 +79,13 @@ void goldfish_tty_early_init(void) {
    write_reg(REG_CMD, CMD_INT_DISABLE);

    // set up the transfer buffer for receives
-    write_reg(REG_DATA_PTR, (uint32_t)transfer_buf);
+    uint32_t buf_addr;
+#if WITH_KERNEL_VM
+    buf_addr = (uint32_t)vaddr_to_paddr(transfer_buf);
+#else
+    buf_addr = (uint32_t)transfer_buf;
+#endif
+    write_reg(REG_DATA_PTR, buf_addr);
    write_reg(REG_DATA_PTR_HIGH, 0);
    write_reg(REG_DATA_LEN, sizeof(transfer_buf));
 }
@@ -103,8 +114,9 @@ int uart_getc(char *c, bool wait) {
 }

 void platform_dputc(char c) {
-    if (c == '\n')
+    if (c == '\n') {
        platform_dputc('\r');
+    }
    uart_putc(c);
 }

--- a/platform/qemu-virt-m68k/pic.c
+++ b/platform/qemu-virt-m68k/pic.c
@@ -8,13 +8,13 @@
 #include "platform_p.h"

 #include <assert.h>
-#include <lk/bits.h>
-#include <lk/err.h>
-#include <lk/debug.h>
-#include <lk/reg.h>
-#include <lk/trace.h>
 #include <kernel/debug.h>
 #include <kernel/thread.h>
+#include <lk/bits.h>
+#include <lk/debug.h>
+#include <lk/err.h>
+#include <lk/reg.h>
+#include <lk/trace.h>
 #include <platform/interrupts.h>
 #include <platform/virt.h>

@@ -31,7 +31,7 @@ enum {
    REG_ENABLE = 0x10,
 };

-volatile uint32_t * const goldfish_pic_base = (void *)VIRT_GF_PIC_MMIO_BASE;
+volatile uint32_t *const goldfish_pic_base = (void *)VIRT_GF_PIC_MMIO_BASE;

 static struct int_handlers {
    int_handler handler;
@@ -128,4 +128,3 @@ enum handler_return m68k_platform_irq(uint8_t m68k_irq) {

    return ret;
 }
-
--- a/platform/qemu-virt-m68k/platform.c
+++ b/platform/qemu-virt-m68k/platform.c
@@ -5,17 +5,18 @@
 * license that can be found in the LICENSE file or at
 * https://opensource.org/licenses/MIT
 */
+#include <dev/virtio.h>
+#include <dev/virtio/net.h>
+#include <kernel/thread.h>
+#include <lk/err.h>
 #include <lk/reg.h>
 #include <lk/trace.h>
-#include <kernel/thread.h>
 #include <platform.h>
-#include <platform/interrupts.h>
 #include <platform/debug.h>
+#include <platform/interrupts.h>
 #include <platform/timer.h>
 #include <platform/virt.h>
 #include <sys/types.h>
-#include <dev/virtio.h>
-#include <dev/virtio/net.h>
 #if WITH_LIB_MINIP
 #include <lib/minip.h>
 #endif
@@ -30,7 +31,38 @@

 #define LOCAL_TRACE 0

+// Add the one memory region we have detected from the bootinfo
+static status_t add_memory_region(paddr_t base, size_t size, uint flags) {
+#if WITH_KERNEL_VM
+    static pmm_arena_t arena;
+
+    arena.name = "mem";
+    arena.base = base;
+    arena.size = size;
+    arena.priority = 1;
+    arena.flags = PMM_ARENA_FLAG_KMAP | flags;
+
+    status_t err = pmm_add_arena(&arena);
+    if (err < 0) {
+        panic("pmm_add_arena failed\n");
+    }
+    return err;
+#else
+    novm_add_arena("mem", base, size);
+    return NO_ERROR;
+#endif
+}
+
 void platform_early_init(void) {
+
+#if M68K_MMU == 68040
+    // use DTTR1 to map in all of peripheral space
+    // map 0xff000000 - 0xffffffff (16MB) to 0xff000000
+    // Logical address base: 0xff000000, mask 0x00000000, enable, supervisor, noncachable, serialized
+    uint32_t ttbr1 = 0xff00a040;
+    asm volatile("movec %0, %%dtt1" ::"r"(ttbr1) : "memory");
+#endif
+
    goldfish_tty_early_init();
    pic_early_init();
    goldfish_rtc_early_init();
@@ -55,7 +87,7 @@ void platform_early_init(void) {
    uint32_t memsize = *(const uint32_t *)((uintptr_t)ptr + 4);

    dprintf(INFO, "VIRT: memory base %#x size %#x\n", membase, memsize);
-    novm_add_arena("mem", membase, memsize);
+    add_memory_region((paddr_t)membase, (size_t)memsize, 0);

    // TODO: read the rest of the device bootinfo records and dynamically locate devices
 }
@@ -65,6 +97,11 @@ void platform_init(void) {
    goldfish_tty_init();
    goldfish_rtc_init();

+#if M68K_MMU == 68040
+    // create a VM reservation for peripheral space thats using DTTR1
+    vmm_reserve_space(vmm_get_kernel_aspace(), "periph", 0x1000000, 0xff000000);
+#endif
+
    /* detect any virtio devices */
    uint virtio_irqs[NUM_VIRT_VIRTIO];
    for (int i = 0; i < NUM_VIRT_VIRTIO; i++) {
@@ -90,7 +127,7 @@ void platform_init(void) {

        virtio_net_start();

-        //minip_start_static(ip_addr, ip_mask, ip_gateway);
+        // minip_start_static(ip_addr, ip_mask, ip_gateway);
        minip_start_dhcp();
    }
 #endif
--- a/platform/qemu-virt-m68k/platform_p.h
+++ b/platform/qemu-virt-m68k/platform_p.h
@@ -7,8 +7,6 @@
 */
 #pragma once

-#include <stdbool.h>
-
 void uart_init(void);

 void pic_early_init(void);
--- a/platform/qemu-virt-m68k/rules.mk
+++ b/platform/qemu-virt-m68k/rules.mk
@@ -4,6 +4,7 @@ MODULE := $(LOCAL_DIR)

 ARCH := m68k
 M68K_CPU := 68040
+WITH_MMU ?= 1
 LK_HEAP_IMPLEMENTATION ?= dlmalloc

 MODULE_DEPS += lib/cbuf
--- a/platform/rosco-m68k/rules.mk
+++ b/platform/rosco-m68k/rules.mk
@@ -4,6 +4,7 @@ MODULE := $(LOCAL_DIR)

 ARCH := m68k
 M68K_CPU := 68010
+WITH_MMU ?= 0
 LK_HEAP_IMPLEMENTATION ?= dlmalloc
 WITH_LINKER_GC ?= true

--- a/scripts/do-qemum68k
+++ b/scripts/do-qemum68k
@@ -8,4 +8,4 @@ set -x
 PROJECT=qemu-virt-m68k-test

 $DIR/make-parallel $PROJECT
-qemu-system-m68k -machine virt -cpu m68040 -kernel build-${PROJECT}/lk.elf -nographic $@
+qemu-system-m68k -machine virt -m 64 -cpu m68040 -kernel build-${PROJECT}/lk.elf -nographic $@
Author	SHA1	Message	Date
Travis Geiselbrecht	b433d4582d	[arch][m68k] careful of PC relative addressing on 68000 and 68010 These cpus only support a simple 16 bit offset from PC, so cannot use it in start.S to compute a large offset. This is okay, because the code that needs it is only for cpus with an MMU, which these dont have.	2025-09-22 21:52:48 -07:00
Travis Geiselbrecht	bb5db64b4c	[arch][m68k] add arch_mmu_query so the kernel boots completely Side effect of editing: reformat all of the code in platform/qemu-virt-m68k	2025-09-22 21:52:48 -07:00
Travis Geiselbrecht	6c7e6a1796	[arch][m68k] start to enable the VM on m68k -Wire up the make plumbing for setting the kernel vm bits -Implement stubbed out arch_mmu routines. -Set up a high mapping in start.S that should be compatible with the mmu code.	2025-09-22 21:52:48 -07:00
Travis Geiselbrecht	5926fb1cc8	[arch][m68k] Initial support for 68040 mmu Currently just sets up most of an identity map and some test mappings. Not fully wired up to the VM yet.	2025-09-07 16:23:16 -07:00