[igt-dev] [PATCH i-g-t v6 9/9] igt/lib: If mappable aperture is missing return 0 size

[Chris Wilson]

Quoting Antonio Argenziano (2019-06-13 22:54:48)
> So far the aperture size has been read directly from the bar,
> in this patch we return zero if the mappable aperture is not available
> as the value stored in the bar is not accurate. The patch also adds a
> 'require' when a call to gem_mappable_aperture_size() is made so that
> the aperture is guaranteed to exist before checking the size.
> 
> Cc: Katarzyna Dec <katarzyna.dec at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Antonio Argenziano <antonio.argenziano at intel.com>
> ---
>  lib/ioctl_wrappers.c            | 28 ++++++++++++++-------
>  lib/ioctl_wrappers.h            |  3 ++-
>  tests/i915/gem_concurrent_all.c | 12 ++++-----
>  tests/i915/gem_cpu_reloc.c      |  4 +--
>  tests/i915/gem_mmap.c           |  4 +--
>  tests/i915/gem_mmap_gtt.c       | 10 ++++----
>  tests/i915/gem_pwrite.c         |  4 +--
>  tests/i915/gem_shrink.c         |  2 +-
>  tests/i915/i915_pm_rpm.c        |  2 +-
>  tests/kms_big_fb.c              |  2 +-
>  tests/kms_flip.c                |  2 +-
>  tests/prime_mmap.c              | 43 ++++++++++++++++++++++++++++++---
>  12 files changed, 81 insertions(+), 35 deletions(-)
> 
> diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> index 280fdd62..58603e0e 100644
> --- a/lib/ioctl_wrappers.c
> +++ b/lib/ioctl_wrappers.c
> @@ -1088,19 +1088,14 @@ uint64_t gem_aperture_size(int fd)
>         return aperture_size;
>  }
>  
> -/**
> - * gem_mappable_aperture_size:
> - *
> - * Feature test macro to query the kernel for the mappable gpu aperture size.
> - * This is the area available for GTT memory mappings.
> - *
> - * Returns: The mappable gtt address space size.
> - */
> -uint64_t gem_mappable_aperture_size(void)
> +static uint64_t __gem_mappable_aperture_size(int fd)
>  {
>         struct pci_device *pci_dev = intel_get_pci_device();
>         int bar;
>  
> +       if (!gem_mmap__has_gtt(fd))
> +               return 0; /* Aperture not available */

Seems sensible, but does strike one as weird. If there is no aperture,
there will be no BAR. Right?

More interesting question is just how many places exploded with a zero
sized aperture?
-Chris