Re: [Qemu-devel] [PATCH] xen: Restrict build to x86 targets

[Alexander Graf]

On 01.12.2010, at 11:21, Anthony PERARD wrote:

> On Mon, 29 Nov 2010, Alexander Graf wrote:
> 
>> 
>> On 29.11.2010, at 15:27, Jan Kiszka wrote:
>> 
>>> Am 29.11.2010 15:15, Alexander Graf wrote:
>>>> 
>>>> On 29.11.2010, at 13:44, Jan Kiszka wrote:
>>>> 
>>>>> Am 29.11.2010 13:40, Alexander Graf wrote:
>>>>>> 
>>>>>> On 29.11.2010, at 13:30, Jan Kiszka wrote:
>>>>>> 
>>>>>>> Am 29.11.2010 13:24, Alexander Graf wrote:
>>>>>>>> 
>>>>>>>> On 28.11.2010, at 16:59, Jan Kiszka wrote:
>>>>>>>> 
>>>>>>>>> From: Jan Kiszka <address@hidden>
>>>>>>>>> 
>>>>>>>>> Xen target bits in qemu are intended for x86. Let the build system
>>>>>>>>> reflect this and avoid useless building/linking for other targets.
>>>>>>>> 
>>>>>>>> Not sure I understand the split. Xen is x86 only, yes. But why split 
>>>>>>>> it into host and target? Target usually defines the guest. The piece 
>>>>>>>> you marked as _HOST are target specific.
>>>>>>> 
>>>>>>> At least so far, the HOST part is build once for all targets into the
>>>>>>> host backend library. As this step injected CONFIG_XEN into all target
>>>>>>> builds, even non-x86 targets built xen_machine_pv and xen_domainbuild.
>>>>>>> That's addressed by the patch.
>>>>>> 
>>>>>> I still don't understand the need for that split.
>>>>> 
>>>>> Enable Xen and build some non-x86 targets, then you see the need.
>>>>> 
>>>>>> The device drivers should be built only once, as do the xen_machine_pv 
>>>>>> parts. Both are useless on non-x86. CONFIG_XEN should simply always be a 
>>>>>> target specific option.
>>>>> 
>>>>> Maybe the split-up between the "generic" host-side interfaces and
>>>>> xen_machine_pv/xen_domainbuild is the problem. You know the dependencies
>>>>> better than me, maybe you find a better fix.
>>>> 
>>>> Should be enough to just replace obj-$(CONFIG_XEN) by 
>>>> obj-i386-$(CONFIG_XEN).
>>> 
>>> Indeed (as long as qemu's xen remains x86-only).
>> 
>> I'm 99.9% sure it will :).
>> 
>>>> Unless it's very urgent, please wait with this patch until qemu-dm and 
>>>> xenner are in. It's pretty suboptimal to have 3 patches flying around that 
>>>> hit the exact same code spot :).
>>> 
>>> It isn't urgent. If patches series refactor the stuff and fix the
>>> dependency, I'm happy to wait for them.
>> 
>> They don't really refactor it, but add a lot more dependencies. Anthony, 
>> since you probably need yet another round for the 4.0 compile stuff, feel 
>> like putting this on your TODO list too? (Sorry this takes so long :( - I'll 
>> try to review stuff quicker next time around)
> 
> OK, but I will go a little further by putting all Xen stuff in x86 only
> target, not only xenpv.

Yes, please. That's perfect :).


Alex