[PATCH 1/2] Revert "include/uapi/drm/amdgpu_drm.h: use __u32 and __u64 from <linux/types.h>"

[Emil Velikov]

On 20 August 2016 at 12:47, Marek Olšák <maraeo at gmail.com> wrote:
> On Sat, Aug 20, 2016 at 1:08 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> On 20 August 2016 at 11:05, Marek Olšák <maraeo at gmail.com> wrote:
>>> On Sat, Aug 20, 2016 at 12:54 AM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>>>> On 19 August 2016 at 15:26, Christian König <deathsimple at vodafone.de> wrote:
>>>>> Am 19.08.2016 um 15:50 schrieb Marek Olšák:
>>>>>>
>>>>>> From: Marek Olšák <marek.olsak at amd.com>
>>>>>>
>>>>>> This reverts commit 2ce9dde0d47f2f94ab25c73a30596a7328bcdf1f.
>>>>>>
>>>>>> See the comment in the code. Basically, don't do cleanups in this header.
>>>>>>
>>>>>> Signed-off-by: Marek Olšák <marek.olsak at amd.com>
>>>>>
>>>>>
>>>>> I completely agree with you that this was a bad move, but I fear that we
>>>>> will run into opposition with that.
>>>>>
>>>> Please check the facts before introducing RATHER ANNOYING AND HARD TO
>>>> READ COMMENT IN ALL CAPS.
>>>>
>>>> Story time:
>>>> I was dreaming of a day were we can stop installing these headers,
>>>> thus making deprecation a bit easier process.
>>>> Yet after failing to convince Dave and Daniel on a number of occasions
>>>> I've accepted that those headers _are_ here to stay. And yes they
>>>> _are_ the UAPI, even though no applications are meant to use them but
>>>> the libdrm 'version'.
>>>> Thus any changes to the libdrm ones should be a mirror of the ones
>>>> here and libdrm should _not_ differ.
>>>>
>>>> But let's ignore all that and imagine that those headers are _not_
>>>> UAPI. That gives us even greater reason to _not_ use the uintx_t types
>>>> but the kernel __uX ones. The series that did these changes had a fair
>>>> few references why we want that.
>>>>
>>>> Yes, I can imagine that the situation isn't ideal, and/or not that
>>>> clear. Then again a check with git log should have straightened things
>>>> out.
>>>> If not _please_ help us improve this (documentation and/or others).
>>>>
>>>>
>>>> And last but not least, please share with up what inspired this -
>>>> (build/runtime) regression, attempted sync with libdrm, other ?
>>>
>>> Syncing with libdrm became difficult.
>> Actually it should be easier now. Perhaps the radeon one was always a
>> good citizen, but sadly that was not the case for the rest.
>>
>>> I'd like the diff between kernel
>>> and libdrm to be as small as possible.
>>>
>> I believe we all agree on this one :-)
>>
>>> We must take into account that the uapi headers can potentially be
>>> implemented by a different OS.
>> Agreed. Have you looked at the 'compatibility layer' in drm.h ?
>>
>>> That's why they are in libdrm and
>>> that's why nobody should make random changes to them in the kernel
>>> tree. Do not think like a kernel developer isolated in Linux and just
>>> consider the broader use case. If you do, you'll realize that it
>>> simply doesn't make sense to use the __uX types here.
>>>
>> Ftr, like Rob (and maybe others) I believe that using __uX (in the
>> kernel) is a bit odd, and opting for the stdint.h types should happen.
>> But until/if that happens we have to live with the __uX ones.
>>
>> That said, I have poked various BSD people on a number of occasions,
>> (hopefully) inspiring them to upstream their changes in a compatible
>> way. Thus the whole "don't think like a kernel developer" doesn't
>> really apply here :-\
>>
>> I'm simply one of the few fools^wpeople trying to make things OK for
>> most (since one can never please everyone, all the time).
>>
>> IIRC the FreeBSD/DragonFly people had some issues with their
>> compatibility layer since the kernel and userspace drm.h were
>> divergent "by design" [1]. To make it even 'better' there's even two
>> difference versions of drm.h in their kernel itself [2].
>>
>> What I am for is a discussion how to resolve things. Although expect
>> resistance if you're thinking about applying tape, in order to fix
>> somethings that's 'broken' elsewhere.
>>
>> If you or any !Linux folks are around on XDC we should really sit down
>> and untangle some/all of these issues.
>
> It's not 100% certain but it looks like we won't be there.
>
> We need the uapi headers to be the same as libdrm ones to make syncing
> easier. There is not much else to discuss here really. We (AMD) are
> also the ones who have to work with these headers the most, not you, not Mikko.
>
Agreed and agreed.

> While I understand some people want to discuss this further, these
> patches must land first in order bring back the compatibility with
> libdrm.
This is where the misunderstanding lies - there _must_ _not_ be
compatible with the libdrm ones, but the other way around. Check the
output of $ git log -p -- include/drm in libdrm. Pretty please ?

> After that, we can discuss the possible solutions and
> everybody interested in a better solution *that will take libdrm into
> account* can join. For now, I have to expect that those discussions
> might also lead nowhere and

> I don't wanna be stuck with bad uapi
> headers in the kernel forever.
>
As mentioned before - please clearly state what do you perceive as bad
and/or why. Daniel, myself and Rob (to a point) have explained that
things are not perfect as-is but they are definitely not bad or wrong.

Thanks
Emil