[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 16:08, Marek Olšák <maraeo at gmail.com> wrote:
> 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.
>
I see two things, neither of which implies any problems.
 - "syncing became difficult" which should _not_ be the case if you're
using make headers_install
 - unease about usage of __uX types and misdirected finger pointing
about compatibility with other OS.

All I can think of is that you (?) are porting some changes from the
kernel to libdrm or vice-versa. In the latter case please _don't_ do
that. Work with your changes in upstream kernel, then pull them down
to libdrm with `make headers_install`.

Thanks
Emil