Add support for RISC-V #121
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Signed-off-by: Ivan Velickovic <[email protected]>
Now we are stuck on this line: 'cpuidle: using governor menu'
Current progress: ``` [ 0.095968] Unpacking initramfs... [ 0.212981] Freeing initrd memory: 16384K [ 0.214101] workingset: timestamp_bits=46 max_order=16 bucket_order=0 [ 0.216709] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 246) [ 0.216914] io scheduler mq-deadline registered [ 0.217026] io scheduler kyber registered [ 0.217192] io scheduler bfq registered VMM|INFO: handling fault 'virtual memory exception' VMM|INFO: fault on addr 0xc002080 VMM|INFO: handling plic 0xc002080 VMM|INFO: satp: 0xa0000000000814f7 Failed assertion '(satp >> 60) == SV39_MODE' at /Users/ivanv/ts/libvmm/src/arch/riscv/fault.c:111 in function guest_virtual_physical ``` now need to deal with PLIC faults Things are a bit concerning because I had to disable two Linux kernel config options: * CONFIG_RISCV_ISA_ZICBOM * CONFIG_RISCV_PROBE_UNALIGNED_ACCESS ZICBOM was causing a vCPU fault, maybe there's something that seL4 needs to allow at VS level that it's not. What's weirder is that program counter in Linux was at the specific point of a no-op instruction which is weird. Secondly, RISCV_PROBE_UNALIGNED_ACCESS was causing some hanging because it's using `rdtime` to determine whether unaligned access is allowed by the hardware. This again is an issue with how we are emulating as the Linux image with both of these configs enabled runs fine bare-metal on QEMU (without seL4 involved.). More investigation required...
Problem is that FPU access in Linux or Linux user-space causes exceptions *in Linux*, which is weird for two reasons: 1. We have the FPU enabled for QEMU in seL4 so I would think that the guest would have FPU access as well. 2. Why is an illegal instruction exception that happened *within Linux* being handled by Linux instead of the VMM?
Timer IRQs are now handled, some fixes in seL4 itself were needed
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Signed-off-by: Ivan-Velickovic <[email protected]>
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This PR adds initial support for RISC-V guests to libvmm.
Right now, only 64-bit guests are supported/tested.
This PR is a draft as there is still much more work to do and more to test/fix such as multiple vCPUs are more complex example systems, but right now a Linux guest can boot and get into user-space.
This PR will likely not be merged for a while as it depends on changes to seL4, which will require an RFC and code review that typically takes months.
To try out this PR, you will need changes a specific branch of Microkit and seL4: