Working on fixing the GEM offset code

src/gpu/i915/mod.rs

@@ -58,6 +58,8 @@ impl From<DrmGemTileInfo> for GemTileInfo {
 }
 
 /// An owned GEM handle that will be closed when dropped
+/// Scoped to a file descriptor - 
+/// this means that it is inherited by `fork` children and can be shared with sendfd
 impl GemHandle<'_> {
     pub fn new(node: &DrmDeviceNode, size: u64) -> Option<GemHandle> {
         uapi::i915::make_gem(node.fd.as_raw_fd(), size).map(|handle| GemHandle {

src/uapi/i915/mod.rs

@@ -284,7 +284,7 @@ pub unsafe fn gem_offset(fd: RawFd, handle: &DrmGemHandle) -> Result<u64, GemIoc
             handle: handle.handle,
             pad: 0,
             offset: 0,
-            flags: native::I915_MMAP_OFFSET_WB as u64,
+            flags: native::I915_MMAP_OFFSET_GTT as u64,
             extensions: 0,
         };
         let res = libc::ioctl(fd, native::DRM_IOCTL_I915_GEM_MMAP_OFFSET, &mut offset);

tests/tests_uapi.rs

@@ -161,6 +161,21 @@ fn test_i915_uapi_gem_fork_parent() {
     }
 }
 
+#[test]
+fn test_i915_uapi_gem_offset() {
+    let nodes = i915::find_all_nodes();
+    unsafe {
+        assert!(nodes.len() > 0);
+        for node in nodes {
+            let gem = i915::make_gem(node.fd.as_raw_fd(), 4096).expect("Failed to make gem");
+            let offset = i915::gem_offset(node.fd.as_raw_fd(), &gem);
+            println!("gem: {:?}, node: {:?}, offset: {:?}", gem, node, offset);
+            assert!(offset.unwrap() > 0);
+            i915::close_gem(node.fd.as_raw_fd(), gem).expect("Failed to close gem");
+        }
+    }
+}
+
 // TODO: Fix this test
 // Shared mem needs to be used to communicate the gem handle between parent and child
 // Test both a shared fd and separate fd