[igt-dev] [PATCH i-g-t v3] lib/i915/gem_mman: Add a helper for obtaining mappable aperture version

[Janusz Krzysztofik]

Hi Chris,

On Friday, May 31, 2019 10:39:47 AM CEST Chris Wilson wrote:
> Quoting Janusz Krzysztofik (2019-05-31 09:33:38)
> > From: Janusz Krzysztofik <janusz.krzysztofik at intel.com>
> > 
> > If a test calls a function which depends on availabiblity of a
> > supported mappable aperture, an error may be reported by the kernel on
> > unsupported hardware.  That may negatively affect results reported by a
> > test framework even if that test ignores the failure and succeedes.
> > 
> > This helper wraps an IOCTL call which returns a version number of a
> > mappable aperture.  It may be used by tests which need to adjust their
> > scope depending on availability of specific version of mappable
> > aperture.
> > 
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at intel.com>
> > Cc: Antonio Argenziano <antonio.argenziano at intel.com>
> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > ---
> > Changelog:
> > v2 (internal) -> v3:
> > - make the code less obsucre, more explicit (Antonio),
> > - reword the helper documentation and commit message.
> > 
> > v1 (internal) -> v2 (internal):
> > - minimize future potential conflicts with 
> >   https://patchwork.freedesktop.org/patch/294053/?series=58551&rev=1
> >   (no progress with than one so not waiting for it any longer):
> >   - convert the helper to a drop-in replacement of the one from the
> >     above mentioned patch, returning mappable aperture version, not
> >     only information on its availability,
> >   - drop any other wrappers,
> > - document the helper,
> > - reword commit message.
> > 
> >  lib/i915/gem_mman.c | 22 ++++++++++++++++++++++
> >  lib/i915/gem_mman.h |  1 +
> >  2 files changed, 23 insertions(+)
> > 
> > diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
> > index 3cf9a6bb..3a3f3e5c 100644
> > --- a/lib/i915/gem_mman.c
> > +++ b/lib/i915/gem_mman.c
> > @@ -40,6 +40,28 @@
> >  #define VG(x) do {} while (0)
> >  #endif
> >  
> > +/**
> > + * gem_mmap__gtt_version:
> > + * @fd: open i915 drm file descriptor
> > + *
> > + * This functions wraps up an IOCTL to obtain mappable aperture version.
> > + *
> > + * Returns: mappable aperture version, -1 on failure.
> > + */
> > +int gem_mmap__gtt_version(int fd)
> > +{
> > +       int gtt_version, ret;
> > +       struct drm_i915_getparam gp = {
> > +               .param = I915_PARAM_MMAP_GTT_VERSION,
> > +               .value = &gtt_version,
> > +       };
> > +
> > +       ret = ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > +       if (ret == 0)
> > +               ret = gtt_version;
> > +       return ret;
> 
> Maybe the actual error returned by the kernel and not glibc would be
> interesting in the future?

errno is not overwritten by the helper so it is available to IGT after it is 
called and actually reported when a call to the helper is wrapped with 
igt_require().  Do we need more?

Thanks,
Janusz

> -Chris
>