Re: qemu direct kernel boot on LoongArch

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 07:25:05AM +0200, Thomas Weißschuh wrote:
> On 2024-09-05 06:04:12+0000, Jason A. Donenfeld wrote:
> > On Thu, Sep 5, 2024 at 5:45 AM maobibo <maobibo@loongson.cn> wrote:
> > >
> > > Jason,
> > >
> > > With the latest qemu 9.1 version, elf format booting is supported.
> > 
> > Thanks, I just figured this out too, about 4 minutes ago. Excellent.
> > And the 1G minimum ram limit is gone too.
> > 
> > Now working on how to trigger resets.
> 
> With "reset" do you mean normal (non-panic) system shutdown/poweroff?
> Since QEMU 9.1 and a recent kernel you can use the pvpanic device for
> that in a cross-architecture way.

What I mean is that I need for userspace calling `reboot(RB_AUTOBOOT);`
to actually result in QEMU being told to reboot the system. Sounds like
that's not possible (yet?) in 9.1?

The last hurdle I'm having, in addition to that one, is getting the
second serial port working. The kernel test suite that I'm running in CI
for /dev/urandom development and wireguard development does `-serial
stdio -serial chardev:result`, where the first serial is the normal
output for logging, and the second one is the test result, so I can get
that from the VM via a clean channel. This works well on other
architectures, but on loongarch, it's failing to open /dev/ttyS1 the
same way that it can open /dev/ttyS0.