This will generally turn off more FPU codegen, even if its using
software fallback unless the project/target/platform selects a cpu that
has FPU support. This also turns off a few blocks of test code and the
upcoming floating point printf if it's not present on the arch.
This may break projects that were compiling for say cortex-m0 but
expected FPU code to be present. If so it should be pretty easy to
override it, but not going to add that yet unless it's necessary.
No real functional change except how the smaller ARCH_DEFAULT_PAGE_SIZE
is now computed and set in defines.h instead of rules.mk for arch/arm to
be consistent with the other arch that has a large/small build (riscv).
To work properly with some hypervisors on various architectures (ARM,
ARM64, x86), add global routines to allow access to MMIO registers via
architecturally defined accessors.
Add accessors for ARM, ARM64, and x86-32/64. Have the other arches
default to just using whatever the compiler emits.
Will need to generally move things off the legacy REG*() accessors
since they're really not safe going forward with what compilers emit.
Port to the really neat 68010 based board at https://rosco-m68k.com/
Port Features:
-10Mhz 68010
-1MB ram
-Dual UART + timer implemented as a 68c681 chip
-timer running at 1Khz, UART A for console
-interrupt driven RX support
Some amount of extending of the 68k exceptinon code was needed to
support the autovectored irqs that the 68681 uart uses. Added build
system support for 68010.
It's non ideal, since there's no relaxation done in the linker so we
have to assume the branch target is > 16 bits away and do what the
compiler usually does and emit a full 32bit jsr.
Mostly rewrote to be cleaner and more obvious what it's doing, but turns
out the real problem was a lack of "memory" and/or volatile. In one of
the test cases the compiler was rearranging the arch_ints_disabled()
check.
Uses the QEMU virt machine for 68k defined in qemu 6.0+.
Basic support that boots, prints to the console, takes input from
console, and context switches.
TODO: interrupt support, timer support.
