Re: [Qemu-devel] [PATCH 1/2] pc: make vgabios exit port more useful

[Anthony Liguori <anthony@codemonkey.ws>]

On 08/24/2011 07:55 AM, Avi Kivity wrote:
> On 08/24/2011 03:38 PM, Anthony Liguori wrote:
>>>
>>>>
>>>> diff --git a/hw/pc.c b/hw/pc.c
>>>> index 1c9d89a..4b07b35 100644
>>>> --- a/hw/pc.c
>>>> +++ b/hw/pc.c
>>>> @@ -549,8 +549,7 @@ static void bochs_bios_write(void *opaque,
>>>> uint32_t addr, uint32_t val)
>>>> /* LGPL'ed VGA BIOS messages */
>>>> case 0x501:
>>>> case 0x502:
>>>> - fprintf(stderr, "VGA BIOS panic, line %d\n", val);
>>>> - exit(1);
>>>> + exit((val<< 1) | 1);
>>>
>>> This code (before the patch) circumvents -no-shutdown.
>>
>>
>> Indeed. I believe that's a feature though?
>
> Depends on what the user of -no-shutdown expects.
>
>>
>>>
>>> Shifting val left is surprising. What's wrong with even exit codes?
>>
>> Hrm, the '| 1' is wrong. My intention was to make the bottom bit of
>> the exit code mean "if set to 0, this is an exit coming from a guest'.
>
> Too subtle, IMO. I understand that we want to avoid a full qmp parser
> for one-off unit tests, but using bit fields in the exit code?
>
> Perhaps a python script that launches qemu with qmp and -no-shutdown,
> listens for the guest shutdown event, and prints out the result? That
> can be easily reused in test scripts.

How can the test pass data via shutdown?  You would need a scratch 
register of some form I think...

Regards,

Anthony Liguori

>