Re: [Qemu-devel] State of KVM bits in linux-headers

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/11/2012 01:32 PM, Alexander Graf wrote:
>
> On 11.01.2012, at 20:16, Jan Kiszka wrote:
>
>> Hi,
>>
>> I'm a bit unhappy about the current state of our supposed to be
>> automatically sync'ed linux-headers directory in qemu. It has been
>> updated several times against undefined kernel trees, means against
>> neither a released version nor kvm.git. Now, if I run an update against
>> kvm.git + some local change, I get a churn of removals. Same will happen
>> when that local change ever goes upstream before the other stuff got
>> finally committed.
>
> Yes, call me even more unhappy about it :(.

May I suggest the following:

1) Have the header syncing script take a commit hash that's stored in git.  Make 
script ensure that this has is in Linus' tree.

2) Maintain a patch on top of Linus' tree in qemu.git that the script would 
apply before actually syncing header files.

That let's us track how we're differing from upstream in a more reliable fashion.

>> Alex, it looks to me like this is mostly PPC stuff. Can you comment on
>> the origin and workflow? E.g. KVM_CAP_SW_TLB: This has been added half a
>> year ago but is not in any Linux release around. Fishy...
>
> Ok, here's my workflow:
>
>    * KVM: receive patches on the ML
>    * KVM: wait for reviews, review myself
>    * KVM: send out a pull request
>    -- this is the point in time where I assume the ABI can be considered stable --
>    * QEMU: run update on the headers, because in a perfect world things should hit kvm.git any day
>    * KVM: pull request gets reviews causing not-pulls or abi changes and lots of churn because i need forever to pullreq again ;)
>
> I guess you see the problem. Hence I haven't pushed any kernel header updates since I realized how badly broken that process was. However even the stuff that's in qemu.git now hasn't managed to get upstream yet.

I don't think it's a broken process.  I think you made a reasonable set of 
assumptions.  I think it was just an exceptional circumstance.

Regards,

Anthony Liguori