Re: [Qemu-devel] [RFC PATCH 0/5] modify boot order when vm is running

[Laszlo Ersek <lersek@redhat.com>]

On 07/07/14 13:12, Gonglei (Arei) wrote:
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>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Monday, July 07, 2014 6:04 PM
>> To: Michael S. Tsirkin; Gonglei (Arei)
>> Cc: qemu-devel@nongnu.org; afaerber@suse.de; agraf@suse.de;
>> stefanha@redhat.com; akong@redhat.com; aik@ozlabs.ru;
>> alex.williamson@redhat.com; armbru@redhat.com; eblake@redhat.com;
>> kwolf@redhat.com; peter.maydell@linaro.org; lcapitulino@redhat.com;
>> pbonzini@redhat.com; kraxel@redhat.com; imammedo@redhat.com;
>> dmitry@daynix.com; marcel.a@redhat.com; peter.crosthwaite@xilinx.com;
>> rth@twiddle.net; somlo@cmu.edu; Huangweidong (C); Luonengjun;
>> Huangpeng (Peter); chenliang (T)
>> Subject: Re: [RFC PATCH 0/5] modify boot order when vm is running
>>
>> On 07/07/14 11:29, Michael S. Tsirkin wrote:
>>> On Mon, Jul 07, 2014 at 05:10:56PM +0800, arei.gonglei@huawei.com
>> wrote:
>>>> From: Chenliang <chenliang88@huawei.com>
>>>>
>>>> Sometime, we want to modify boot order of vm without shutdown it.
>>>> This sets of patches add one qmp to achieve it. And fix some little
>>>> bug when device is hotpluged.
>>>>
>>>> Chenliang (5):
>>>>   bootindex: add *_boot_device_path function
>>>>   bootindex: reset bootindex when vm reset
>>>>   bootindex: delete boot index when device is removed
>>>>   bootindex: add qmp to set boot index when vm is running
>>>>   bootindex: fix memory leak when ppc sets boot index
>>>
>>> Unfortunately at least for PC, boot order is exposed
>>> in fw cfg which can not change while guest is running.
>>> I suspect we need to change how we report boot order to guests.
>>> While we are at it, maybe we can fix the silly bootindex
>>> convention: I think people really want to specify boot *order*,
>>> not boot index.
>>
>> Please preserve the "bootorder" fw_cfg file, and its format.
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>> I don't have any request in relation to the new (== dynamic) feature ATM.
>>
> Sorry, I can't understand your meaning exactly. 
> Would you explain it? Thanks!

I meant that whatever features you introduce, please make sure that a
guest looking for the "bootorder" fw_cfg file will find it, and that the
contents and the format of that fw_cfg file stays the same, for the same
qemu command line options.

I'm not implying that your current series changes the "bootorder" fw_cfg
file (I have not looked at your patches); this is just a general request
I make out of caution.

Thanks
Laszlo