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Re: [Qemu-devel] [PATCH] vl: don't use RUN_STATE_PRECONFIG unless --prec
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH] vl: don't use RUN_STATE_PRECONFIG unless --preconfig is given |
Date: |
Mon, 4 Jun 2018 12:33:04 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 2018-06-04 12:27, Daniel P. Berrangé wrote:
> The RUN_STATE_PRECONFIG state is not supposed to be reachable unless the
> --preconfig argument is given to QEMU, but when it was introduced in:
>
> commit 047f7038f586d2150f16c6d9ba9cfd0479f0f6ac
> Author: Igor Mammedov <address@hidden>
> Date: Fri May 11 19:24:43 2018 +0200
>
> cli: add --preconfig option
>
> The global 'current_run_state' variable was changed to have an initial
> value of RUN_STATE_PRECONFIG regardless of whether --preconfig is given.
>
> It then relies on the main loop to toggle it back to RUN_STATE_PRELAUNCH
> when --preconfig is not given. This is racy because it means that there
> is a window where QEMU is in RUN_STATE_PRECONFIG despite --preconfig not
> being given. This can be seen with the failure:
>
> $ echo | x86_64-softmmu/qemu-system-x86_64 -monitor stdio
> QEMU 2.12.50 monitor - type 'help' for more information
> (qemu)
> HMP not available in preconfig state, use QMP instead
>
> Signed-off-by: Daniel P. Berrangé <address@hidden>
> ---
> vl.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
This indeed fixes the issue that the preconfig state is reachable
without --preconfig, but it still keeps the main loop being invoked
twice (which means that e.g. HMP will process a single character before
the main loop is actually really invoked:
$ echo quit | x86_64-softmmu/qemu-system-x86_64 \
-drive file=/dev/null,if=ide,readonly=on -monitor stdio
QEMU 2.12.50 monitor - type 'help' for more information
(qemu) qqemu-system-x86_64: Initialization of device ide-hd failed:
Block node is read-only
(Note the "q" before "qemu-system-x86_64"))
(Naively,) I agree with Michal that the main loop should only be invoked
twice if --preconfig has been given, which is implemented by his patch:
http://lists.nongnu.org/archive/html/qemu-devel/2018-06/msg00367.html
Max
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