Re: [PATCH 1/4] conf: add loader type 'none'
On Tue, Apr 11, 2023 at 01:14:27PM +0200, Gerd Hoffmann wrote:
> The second approach is the one described in the Ubuntu wiki[3],
and
> also requires passing two files to QEMU, except this time they come
> from the opensbi and u-boot-qemu packages respectively. The usage
> looks like
>
> -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.elf
> -kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf
>
> I think in this case the first file is a minimal build of OpenSBI
> that likely just initializes enough hardware before handing control
> to an arbitrary payload - in this case, u-boot.
Yes. These days opensbi seems to be loaded by default, so the first
line is not needed. In fact I'm running a guest here, on fedora 37 +
virt-preview with just this ...
<os>
<type arch='riscv64' machine='virt'>hvm</type>
<kernel>/home/kraxel/projects/u-boot/build-qemu-riscv64-smode/u-boot.bin</kernel>
<boot dev='hd'/>
</os>
... and it works fine.
This matches my experience.
I've tried both u-boot.bin (referenced in openSUSE and FreeBSD
documentation) and uboot.elf (Debian and Ubuntu documentation) and it
doesn't seem to make a difference which one you choose.
There is also this variant ...
<qemu:commandline>
<qemu:arg value='-drive'/>
<qemu:arg
value='if=pflash,index=1,format=raw,file=/vmdisk/hdd/pool-risc-v/RISCV_VIRT.raw'/>
</qemu:commandline>
... to boot edk2 firmware. Note this is a single image carrying both
code and vars. Also note 'index=1', which I think is needed because the
(default) opensbi is loaded to the pflash device with 'index=0'.
This doesn't boot the distro due to grub2 not having full riscv64 efi
support (yet).
The openSUSE images are using grub2, and possibly EFI somehow?
Right after selecting the entry I see
EFI stub: Booting Linux Kernel...
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Using DTB from configuration table
EFI stub: Exiting boot services...
The image never manages to boot all the way for me: it looks like it
can't find the root filesystem. But eventually I get dropped into a
rescue shell, and /sys/firmware/efi/ contains some data.
Note that I'm not using edk2 in this case, just the same u-boot.bin
file that I've used to boot other images.
--
Andrea Bolognani / Red Hat / Virtualization