Re: [git pull] drm request 3

From: Maarten Maathuis
Date: Thu Mar 04 2010 - 16:23:00 EST

On Thu, Mar 4, 2010 at 10:21 PM, Maarten Maathuis <madman2003@xxxxxxxxx> wrote:
> On Thu, Mar 4, 2010 at 7:18 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> Hmm. What the hell am I supposed to do about
>>        (II) NOUVEAU(0): [drm] nouveau interface version: 0.0.16
>>        (EE) NOUVEAU(0): [drm] wrong version, expecting 0.0.15
>>        (EE) NOUVEAU(0): 879:
>> now?
>> What happened to the whole backwards compatibility thing? I wasn't even
>> warned that this breaks existing user space. That makes it impossible to
>> _test_ new kernels. Upgrading X and the kernel in lock-step is not a valid
>> model, lots of people are just using some random distribution (F12 in my
>> case), and you just broke it.
>> I see the commit that does this was very aware of it:
>>        commit a1606a9596e54da90ad6209071b357a4c1b0fa82
>>        Author: Ben Skeggs <bskeggs@xxxxxxxxxx>
>>        Date:   Fri Feb 12 10:27:35 2010 +1000
>>            drm/nouveau: new gem pushbuf interface, bump to 0.0.16
>>            This commit breaks the userspace interface, and requires a new libdrm for
>>            nouveau to operate again.
>>            The multiple GEM_PUSHBUF ioctls that were present in 0.0.15 for
>>            compatibility purposes are now gone, and replaced with the new ioctl which
>>            allows for multiple push buffers to be submitted (necessary for hw index
>>            buffers in the nv50 3d driver) and relocations to be applied on any buffer.
>>            A number of other ioctls (CARD_INIT, GEM_PIN, GEM_UNPIN) that were needed
>>            for userspace modesetting have also been removed.
>>            Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
>>            Signed-off-by: Francisco Jerez <currojerez@xxxxxxxxxx>
>> but why the hell wasn't I made aware of it before-hand? Quite frankly, I
>> probably wouldn't have pulled it.
>> We can't just go around breaking peoples setups. This driver is, like it
>> or not, used by Fedora-12 (and probably other distros). It may say
>> "staging", but that doesn't change the fact that it's in production use by
>> huge distributions. Flag days aren't acceptable.
>>                Linus
>> ------------------------------------------------------------------------------
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> What i'm about to say is my personal opinion, not that of nouveau as a
> whole (not even sure if such a thing exists).
> 1. We are in staging because our abi isn't final yet.
> 2. We (already) adjusted our way of working to ensure we have a usable
> and proper codebase by the time we are ready for mainline.
> 3. Redhat through Ben Skeggs contributes to nouveau (quite a bit i agree).
> 4. You are forcing red hat to force something on the rest of us.
> 5. I for one am happy we keep a clean api.
> 6. We keep an internal kernel tree that is tested to some degree (in
> this case the abi break was in there for a few weeks iirc) none of the
> developers asked for a revert.

Point 6 is iirc, someone can correct me if this is not the case.

> 7. Everyone (users, distros) are (or should) be aware of the nature of
> this driver, our userspace interface is experimental for that very
> reason.
> 8. Experience has tought me that in the case of nouveau, if a
> developer isn't using a codepath it will bitrot.
> So please, also take into consideration that this project isn't solely
> made by red hat and it's usually the other people that get to keep the
> pieces.
> Sincerely,
> Maarten Maathuis.
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