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

[Marek Olšák]

On Sat, Aug 20, 2016 at 2:20 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> 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.

The problem is the diff is different, which has been said many times.

Marek