Re: VirtIO MMIO for amd64

[Emile 'iMil' Heitor <imil%home.imil.net@localhost>]

Update

I've got current/amd64 booting on an MMIO-backed block device
with qemu's microvm machine, in both ACPI and command-line-hack
(which passes the "device" address as a kernel parameter).

If anybody wants to give it a try:

$ qemu-system-x86_64 -M microvm,rtc=on -enable-kvm -m 256 -cpu host 
-kernel netbsd.gdb -append "root=ld0a console=com rw" -serial stdio 
-display none -device virtio-blk-device,drive=hd0 -drive 
file=netbsd.img,format=raw,id=hd0 -no-acpi

Note the "rtc=on", without this init_main.c/inittodr(rootfstime)
hangs.

On the other hand, Firecracker loops on an init sig11 crash, I
suspect that might also be related to RTC, I guess I'll have to port
a virtio RTC.

The branch with this feature is here 
https://github.com/NetBSDfr/NetBSD-src/tree/mmio_cmdline
It includes the GENPVH mode to boot the NetBSD kernel from
qemu's -kernel flag.
You'll need at least those two:

virtio* at cmdlinebus?
#virtio* at acpi?
ld*	at virtio?			# Virtio disk device

As previously said, virtio* at acpi? also works.

--
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Emile `iMil' Heitor <imil@{home.imil.net,NetBSD.org}> | https://imil.net