Re: [Intel-gfx] [PATCH v3 09/13] drm/i915/selftests: skip the mman tests for stolen

[Matthew Auld <matthew.auld@intel.com>]

On 29/06/2022 17:22, Thomas Hellström wrote:
> 
> On 6/29/22 14:14, Matthew Auld wrote:
>> It's not supported, and just skips later anyway. With small-BAR things
>> get more complicated since all of stolen is likely not even CPU
>> accessible, hence not passing I915_BO_ALLOC_GPU_ONLY just results in the
>> object create failing.
>>
>> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: Jon Bloomfield <jon.bloomfield@intel.com>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>> Cc: Kenneth Graunke <kenneth@whitecape.org>
>> Cc: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
>> ---
>>   drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
> 
> This reminds me,
> 
> Is there a problem for fbdev (and hence things like plymouth) if the 
> initial fbdev image ends up as a stolen memory object which in turn ends 
> up not being mappable? I remember we discussed this before but can't 
> recall what the answer was.

On discrete the initial-fb looks to be allocated directly from lmem (at 
least on the machines I've seen in CI). See 7fe7c2a679dc ("drm/i915: 
fixup the initial fb base on DGFX"). And from what I could tell the 
offset in lmem is always at the beginning somewhere, which makes sense 
given stuff like small-BAR. But yeah, the create_at() helper should 
complain if someone tried to allocate the initial-fb or similar outside 
the mappable part. IIRC the only user of stolen-lmem is fbc, but that 
doesn't seem to need CPU access.

> 
> Anyway, for this patch
> 
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> 
> 
> 
> 
> 
>>
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c 
>> b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>> index 5bc93a1ce3e3..388c85b0f764 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>> @@ -979,6 +979,9 @@ static int igt_mmap(void *arg)
>>           };
>>           int i;
>> +        if (mr->private)
>> +            continue;
>> +
>>           for (i = 0; i < ARRAY_SIZE(sizes); i++) {
>>               struct drm_i915_gem_object *obj;
>>               int err;
>> @@ -1435,6 +1438,9 @@ static int igt_mmap_access(void *arg)
>>           struct drm_i915_gem_object *obj;
>>           int err;
>> +        if (mr->private)
>> +            continue;
>> +
>>           obj = __i915_gem_object_create_user(i915, PAGE_SIZE, &mr, 1);
>>           if (obj == ERR_PTR(-ENODEV))
>>               continue;
>> @@ -1580,6 +1586,9 @@ static int igt_mmap_gpu(void *arg)
>>           struct drm_i915_gem_object *obj;
>>           int err;
>> +        if (mr->private)
>> +            continue;
>> +
>>           obj = __i915_gem_object_create_user(i915, PAGE_SIZE, &mr, 1);
>>           if (obj == ERR_PTR(-ENODEV))
>>               continue;
>> @@ -1727,6 +1736,9 @@ static int igt_mmap_revoke(void *arg)
>>           struct drm_i915_gem_object *obj;
>>           int err;
>> +        if (mr->private)
>> +            continue;
>> +
>>           obj = __i915_gem_object_create_user(i915, PAGE_SIZE, &mr, 1);
>>           if (obj == ERR_PTR(-ENODEV))
>>               continue;