[Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[ChenLiang]

hi,all
Qemu can not modify boot index when vm is running.
It is inconvenience when we install guest os. Is it
necessary to achieve modify boot index online?
We can add one qmp interface to achieve it.

Re: [Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[Eric Blake]

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On 06/25/2014 04:28 AM, ChenLiang wrote:
> hi,all
> Qemu can not modify boot index when vm is running.

So? Boot index is used exactly once - when the domain is started. After
that, you aren't booting any more, so what benefit is there to changing
boot index on the fly?

> It is inconvenience when we install guest os. Is it
> necessary to achieve modify boot index online?

virt-install manages to install guests just fine without changing the
boot index on the fly; it manages to sequence multiple qemu runs with
different boot indices between runs.

> We can add one qmp interface to achieve it.

You're welcome to submit a patch if you think you have a use case; but I
personally don't see the current setup as limiting.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[Paolo Bonzini]

Il 25/06/2014 15:27, Eric Blake ha scritto:
>> > Qemu can not modify boot index when vm is running.
> So? Boot index is used exactly once - when the domain is started. After
> that, you aren't booting any more, so what benefit is there to changing
> boot index on the fly?
>

It's also used when you reboot.  However, there are currently 
pre-existing bugs in bootindex handling (especially regarding hotplug 
and hot-unplug) that should be fixed before allowing modification of 
boot index while the VM is running.

The command to do the modification could be qom-set.  We can make the 
bootindex property runtime-modifiable.

Paolo

Re: [Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[陈梁]

> Il 25/06/2014 15:27, Eric Blake ha scritto:
>>>> Qemu can not modify boot index when vm is running.
>> So? Boot index is used exactly once - when the domain is started. After
>> that, you aren't booting any more, so what benefit is there to changing
>> boot index on the fly?
>> 
> 
> It's also used when you reboot.  However, there are currently pre-existing bugs in bootindex handling (especially regarding hotplug and hot-unplug) that should be fixed before allowing modification of boot index while the VM is running.
> 

yeah, it is.
> The command to do the modification could be qom-set.  We can make the bootindex property runtime-modifiable.
> 

ok, I will try to achieve it.

Best regards
chenliang
> Paolo
> 

Re: [Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?

[陈梁]

> On 06/25/2014 04:28 AM, ChenLiang wrote:
>> hi,all
>> Qemu can not modify boot index when vm is running.
> 
> So? Boot index is used exactly once - when the domain is started. After
> that, you aren't booting any more, so what benefit is there to changing
> boot index on the fly?
> 
>> It is inconvenience when we install guest os. Is it
>> necessary to achieve modify boot index online?
> 
> virt-install manages to install guests just fine without changing the
> boot index on the fly; it manages to sequence multiple qemu runs with
> different boot indices between runs.

Thanks for your advice. I will try it.
> 
>> We can add one qmp interface to achieve it.
> 
> You're welcome to submit a patch if you think you have a use case; but I
> personally don't see the current setup as limiting.
> 

There is one case when reboot in vm. 

Best regards
chenliang
> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
> 

Re: [Qemu-devel] 答复: [question] Is it, valuable to achieve modify boot index when vm is running?

[ChenLiang]

> ________________________________________

> 发件人: qemu-devel-bounces+yukewei=kingsoft.com@nongnu.org [qemu-devel-bounces+yukewei=kingsoft.com@nongnu.org] 代表 ChenLiang [chenliang88@huawei.com]
> 发送时间: 2014年6月25日 18:28
> 收件人: qemu-devel@nongnu.org
> 抄送: Paolo Bonzini
> 主题: [Qemu-devel] [question] Is it, valuable to achieve modify boot index when vm is running?
> 
> hi,all
> Qemu can not modify boot index when vm is running.
> It is inconvenience when we install guest os. Is it
> necessary to achieve modify boot index online?
> We can add one qmp interface to achieve it.
> 
> cc: qemu-discuss
> Do you mean changing the boot option without closing QEMU process?
> If so, it is a good demand. 


yeah, I mean it.

> --
> Best Regards,
> Kewei