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

[Tvrtko Ursulin]

On 24/01/2020 12:23, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2020-01-24 12:17:58)
From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

We also need to support copying across file descriptors.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Sreedhar Telukuntla <sreedhar.telukun...@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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