Re: [PATCH 1/3] xen/arm: Sync sysregs and cpuinfo with Linux 5.18-rc3

[Bertrand Marquis <Bertrand.Marquis@arm.com>]

Hi Julien,

> On 11 May 2022, at 16:20, Julien Grall <julien@xen.org> wrote:
> 
> Hi,
> 
> On 11/05/2022 15:41, Bertrand Marquis wrote:
>>> On 10 May 2022, at 03:03, Stefano Stabellini <sstabellini@kernel.org> wrote:
>>> 
>>> On Wed, 4 May 2022, Julien Grall wrote:
>>>>> Do I understand right that it is ok for you if I push one patch mentioning
>>>>> all the commits done in Linux corresponding to the changes (instead of one
>>>>> patch per commit) ?
>>>> 
>>>> For this case yes.
>>> 
>>> I managed to do a review of the patch by doing a diff of the relevant
>>> portion of Xen cpufeature.c with Linux cpufeature.c (from commit
>>> b2d229d4ddb1), and the relevant portion of Xen sysregs.h with Linux
>>> sysregs.h (diff -E -b -u).
>>> 
>>> Everything checks out.
>>> 
>>> In my opinion, this patch should be split in 2 patches: the changes to
>>> cpufeature.c and sysregs.c that come from the Linux sources; and the
>>> updates to cpufeature.h that do not. If you do that you can add my
>>> reviewed-by to the first patch with the changes from Linux.
>>> 
>>> The list of individual commit IDs would be nice, but thanksfully the two
>>> source files are still "diffable" so in my opinion are not required.
>> I agree with that.
>> Julien: Do you agree if I just put the changes to cpufeature.h in a separate patch ?
>> I started to list the commit IDs corresponding to the changes in Linux and this would
>> end up with 5 or more which I do not think would be that useful as the diff can be easily
>> done as Stefano mentioned.
> 
> It looks like there are some confusion why I asked the list of commit. For this case, this is not about diffing the code (it is easy to do and I have already done that). It is more about authorship and where the patches come from.

This is clear from the commit message as I give the commit in Linux used so the history can be easily found from that.
I am a bit lost on the authorship part ...

> 
> Technically, speaking you only copied the code from Linux and therefore you are not the author of some of the changes.
> 
> For such case, our general process is:

Could you tell me where this process is described ?

> 1) Backport the commit as-is (i.e the Author is the original Author)
> 2) Add the tag Origin (recently introduced)
> 3) Add your signed-off-by

So following this theory, if we import a file from Linux we should list all the people who contributed to it since it was created ?

> 
> I understand the patch is already written, so I was OK if you simply list of the commits with the authors/tags for this time.

I would like to understand where this requirement is coming from.

@George: is there some kind of legal reason for something like that ?

> 
> If both Stefano and you agree to not keep the authorships, then I will not stand against it. However, I will not get involved in committing and adding my ack.

I want first to clear up this process and understand why you are requesting this to know how I should do anything like that in the future.

Cheers
Bertrand

> 
> Cheers,
> 
> -- 
> Julien Grall