Re: [Qemu-devel] [PATCH 2/2] bootdevice: add check in restore_boot_order()

[Gonglei <arei.gonglei@huawei.com>]

On 2015/1/30 15:46, Markus Armbruster wrote:

> Gonglei <arei.gonglei@huawei.com> writes:
> 
>> On 2015/1/30 0:03, Alexander Graf wrote:
>>
>>>
>>>
>>> On 29.01.15 14:29, arei.gonglei@huawei.com wrote:
>>>> From: Gonglei <arei.gonglei@huawei.com>
>>>>
>>>> If boot order is invaild or is set failed,
>>>> exit qemu.
>>>>
>>>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>>>
>>> Do we really want to kill the machine only because the boot device
>>> string doesn't validate?
>>>
>>
>> Not all of the situation. If people want to change boot order by qmp/hmp
>> command, it just report an error, please see do_boot_set(). But if the boot
>> order is set in qemu command line, it will exit qemu if the boot device string
>> is invalidate, as this patch's situation, which follow the original processing
>> way (commit ef3adf68).
> 
> I think Alex isn't concerned about the monitor command, but what happens
> when boot order "once" is reset to "order" on system reset.
> 
> -boot errors should have been detected during command line processing
> (strongly preferred) or initial startup (acceptable).  Detecting

Yes, and it had done it just like that, please see main() of vl.c. So, actually
it wouldn't fail in the check of restore_boot_order function's calling.
The only possible fails will happen to call boot_set_handler(). Take
x86 pc machine example, set_boot_dev() callback  may return errors.

> configuration errors during operation is nasty.  In cases where we can't
> avoid it (and I'm not sure this is one), we need to consider very
> carefully whether the error should be fatal.

Indeed, maybe we only need to set boot order failed  and report
an error message in this scenario, do you agree?

Regards,
-Gonglei