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.
Use the new github actions to replace the travis-ci builders which
seem to no longer work and are being removed.
This first stab is fairly rough, just matches the explicit matrix
that was in the travis-ci hooks, but at least gets back to a buildable
state again.
Previous to now it had always relied on a custom patched gcc
and a custom sim. In the interim since the initial port went in
some time in 2015 GCC and QEMU have both officially picked up support
for the architecture and the machine that was emulated in the previous
emultor.
Using gcc 10.2 fix up the build and get it basically working. Timers
seem to not be working right but it's probably fairly easy to fix.
-Fix plic driver to handle machine vs supervisor mode
-Add switch to scripts/do-qemuriscv to run in supervisor mode (with OpenSBI)
-Use the FDT to detect the number of cpus and size of memory
Very little needed to port except to conditionalize some assembly in the
context switch and exception code. Mostly needed to move build system
stuff around and add a new project.
The virt machine is a generic target, much like the arm virt machine.
Intended to be simple to use and a good target to run large systems like
linux on. At the moment simply support booting and simple uart and timer
support.
-added support for bringing up the clocks and setting up the gpio bits
before starting the uart.
-add a proper target init routine
-add scripts to flash board via openocd
-fixed bug in riscv interrupt save state where it wasn't saving mstatus
on irq entry.
-comment out cycle enabling, not implemented on this core
-Add support for x86 legacy mode, designed for 386+ instead of pentium+
-Fixup uart driver to support com2
-Stub out PCI driver properly
-Fixup IDE driver to detect legacy disks
Currently targets qemu's sifive_e machine, which is a split flash/ram
machine, much like the Sifive HiFive1. Untested as of yet on a real
HiFive1.
Basic support including interrupts and architectural timers in place.
From scratch simple binning heap. Complexity wise in the middle
between miniheap and dlmalloc. Generally much faster than miniheap
with a small amount of memory overhead. Performs similarly to
dlmalloc.
-Bump the kernel forward by 64K
-Look for the FDT that qemu leaves around in the space just before the kernel
-Pick out the 'memory' node, parse the base/length values and patch the main
pmm arena before adding it
