Re: Could we document exact steps for loongson3-virt in the manual?

[Peter Maydell]

On Tue, 6 Apr 2021 at 14:23, Alex Bennée <alex.bennee@linaro.org> wrote:
>
> Hi,
>
> I was trying to bootstrap a Loongson3 Debian image but ran into some
> roadblocks. Philippe pointed me at:
>
>   https://www.mail-archive.com/qemu-devel@nongnu.org/msg768848.html
>
> which gives a bit of detail but elides over details such as how to
> handle block devices. AFAICT it should support virtio-blk although maybe
> Debian bullseye doesn't support the target, it's hard to say:
>
>   ./qemu-system-mips64el -M loongson3-virt -m 4096 -nographic -blockdev 
> driver=raw,node-name=hd0,discard=unmap,file.driver=host_device,file.filename=/dev/zvol/hackpool-0/debian-bullseye-mips64le
>  -device virtio-blk,drive=hd0 -kernel ./vmlinuz-5.9.0-4-loongson-3 -initrd 
> initrd.gz -append "root=/dev/sda1 console=tty0 nokaslr"
>
> Gets as far as:
>
> [    0.008641] printk: console [tty0] enabled
> [    0.009507] printk: bootconsole [early0] disabled
>
> and then just goes silent.

Oddly enough somebody on stackoverflow had the same problem for
a different board (malta) the other day:
https://stackoverflow.com/questions/66904366/qemu-system-mips-stuck-after-console-tty0-enabled/66910192

As Jiaxun says, the problem is that your kernel command line says "send the
console output to the virtual console on the graphics device (tty0)" but your
QEMU command line is using a serial console and not trying to use graphics.
So as soon as the kernel gets to the point where it can honour your request
it disables the early-boot console and enables tty0 and then you don't
see anything any more :-)

thanks
-- PMM