[RFC PATCH 3/3] libdrm: user mode helper for ipvr drm driver

Daniel Stone daniel at fooishbar.org
Tue Oct 28 09:56:03 PDT 2014


Hi,

On 17 October 2014 01:36, Jiang, Fei <fei.jiang at intel.com> wrote:

> Thanks for Emil's suggestion. You are right, we need make sure structure
> size aligned on 8 bytes, which is important for 32bit-64bit compatible case.


While you're at it, please don't use enum as a type inside ioctls, since
the size can vary by compiler. Please use a uint32_t or whatever instead,
assigning enum values to that.

Cheers,
Daniel

Fei
> -----Original Message-----
> From: Emil Velikov [mailto:emil.l.velikov at gmail.com]
> Sent: Thursday, October 16, 2014 11:20 PM
> To: Cheng, Yao; intel-gfx at lists.freedesktop.org
> Cc: emil.l.velikov at gmail.com; Jiang, Fei; dri-devel at lists.freedesktop.org;
> Vetter, Daniel
> Subject: Re: [RFC PATCH 3/3] libdrm: user mode helper for ipvr drm driver
>
> On 16/10/14 15:33, Cheng, Yao wrote:
> > Hi Emil,
> > Sorry, what do you mean by "correctly aligned"? does it mean the
> paddings in this data structure?
> >
> Afaict for compatibility reasons the struct size have to be "aligned"
> (multiple of 8 bytes), or if you prefer - the struct is missing the
> required padding :) I've only skimmed through the patch so it may be that
> other structs are having this issue.
>
> Cheers,
> Emil
>
> >> -----Original Message-----
> >> From: Emil Velikov [mailto:emil.l.velikov at gmail.com]
> >> Sent: Wednesday, October 15, 2014 5:24 PM
> >> To: Cheng, Yao; intel-gfx at lists.freedesktop.org
> >> Cc: emil.l.velikov at gmail.com; Jiang, Fei;
> >> dri-devel at lists.freedesktop.org; Vetter, Daniel
> >> Subject: Re: [RFC PATCH 3/3] libdrm: user mode helper for ipvr drm
> >> driver
> >>
> >> Hi Yao,
> >>
> >> struct drm_ipvr_gem_userptr does not seem to be correctly aligned -
> >> is that intentional ? Might be worth checking if anything else in
> >> ipvr_drm.h and ipvr_bufmgr.h is in the same boat.
> >>
> >> Cheers,
> >> Emil
> >>
>
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