Re: RFC: xfree: dri2: libdrm as optional

[Oliver McFadden <oliver.mcfadden@nokia.com>]

On Tue, 2010-01-19 at 20:18 +0100, Vignatti Tiago (Nokia-D/Helsinki)
wrote:
> Some drivers use DRI2 protocol but implement their own kernel rendering
> mananger. For these drivers, libdrm becomes useless.
> 
> The only inconvenient right now to put libdrm optional to X server is
> concerning DRI2Authenticate. Such function uses drm_magic_t and drmAuthMagic
> symbols from libdrm. So I thought two alternatives.
> 
> 1. wrap with some macros and set at compilation time:
> 
>     #ifndef WITH_DRM
>     typedef unsigned int drm_magic_t;
>     #endif
> 
>     Bool
>     DRI2Authenticate(ScreenPtr pScreen, drm_magic_t magic)
>     {
>     #ifdef WITH_DRM
>         DRI2ScreenPtr ds = DRI2GetScreen(pScreen);
> 
>         if (ds == NULL || drmAuthMagic(ds->fd, magic))
>            return FALSE;
> 
>         return TRUE;
>     #else
>         return FALSE;
>     #endif
>     }
> 
> 
> 2. hide all trickery inside xorg driver, adding a new field to DRI2InfoRec:
> 
>     Bool
>     DRI2Authenticate(ScreenPtr pScreen, unsigned int magic)
>     {
>         DRI2ScreenPtr ds = DRI2GetScreen(pScreen);
>         if (ds == NULL || (*ds->AuthMagic)(ds->fd, magic))
>         return FALSE;
> 
>         return TRUE;
>     }
> 
> 
> In the first alternative the implementation is straightforward but should be
> adjusted at build time. It's ugly. Also, one would want to implement his own
> way of clients authentication, or not (sigh) - note though dri2proto states
> that this is not mandatory:
> 
>     "A kernel rendering manager can choose not to implement any
>     authentication and just allow access to all buffers."
> 
> Alternative 2. seems more complete but requires code changes all over the
> drivers. I'm more inclined for this alternative... Moreover, for both
> alternatives we need to do something with drm_magic_t type - can we just use
> unsigned int instead declare such new type?

Does it really matter that we would leave the drm_magic_t typedef
defined? In this case, we would just have one ifdef inside
DRI2Authenticate().

But I agree, moving the auth checking into a function in DRI2InfoRec
might be the nicest solution but harder to get in considering it touches
all the drivers.

> So what you guys think about this all?
> 
> 
> Thanks,
> 
>             Tiago
> _______________________________________________
> xorg-devel mailing list
> xorg-devel@lists.x.org
> http://lists.x.org/mailman/listinfo/xorg-devel



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