Re: [igt-dev] [PATCH i-g-t 1/2] lib/i915: Add helper for copying engine maps from one context to another

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 24/01/2020 12:23, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2020-01-24 12:17:58)
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> We also need to support copying across file descriptors.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Sreedhar Telukuntla <sreedhar.telukuntla@intel.com>
>> ---
>>   lib/i915/gem_context.c | 30 ++++++++++++++++++++++++++++++
>>   lib/i915/gem_context.h |  2 ++
>>   2 files changed, 32 insertions(+)
>>
>> diff --git a/lib/i915/gem_context.c b/lib/i915/gem_context.c
>> index 0b6a554dfe27..41957b66ca52 100644
>> --- a/lib/i915/gem_context.c
>> +++ b/lib/i915/gem_context.c
>> @@ -462,3 +462,33 @@ bool gem_context_has_engine(int fd, uint32_t ctx, uint64_t engine)
>>   
>>          return __gem_execbuf(fd, &execbuf) == -ENOENT;
>>   }
>> +
>> +/**
>> + * gem_context_copy_engines:
>> + * @src_fd: open i915 drm file descriptor where @src context belongs to
>> + * @src: source engine map context id
>> + * @dst_fd: open i915 drm file descriptor where @dst context belongs to
>> + * @dst: destination engine map context id
>> + *
>> + * Special purpose wrapper for copying engine map from one context to another.
>> + *
>> + * In can be called regardless of whether the kernel supports context engine
>> + * maps and is a no-op if not supported.
>> + */
>> +void
>> +gem_context_copy_engines(int src_fd, uint32_t src, int dst_fd, uint32_t dst)
>> +{
>> +       I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, I915_EXEC_RING_MASK + 1);
>> +       struct drm_i915_gem_context_param param = {
>> +               .param = I915_CONTEXT_PARAM_ENGINES,
>> +               .ctx_id = src,
>> +               .size = sizeof(engines),
>> +               .value = to_user_pointer(&engines),
>> +       };
>> +
>> +       if (__gem_context_get_param(src_fd, &param) || !param.size)
>> +               return;
>> +
>> +       param.ctx_id = dst;
>> +       gem_context_set_param(dst_fd, &param);
> 
> You don't want to copy across the use-default set? You presume dst is
> already using defaults?

Hm hm.. not sure. I guess it would be most in-line with what the helper 
say on the tin to copy as is. I'll respin.

Regards,

Tvrtko
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