posix: implement PRIME for fd <-> handle conversion #419
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| auto ret = _buffers.insert({handle, bo}); | ||
| assert(ret.second); |
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Hopefully not, but this is a sanity check to catch the (unlikely) case of duplicate handles.
core/drm/src/core.cpp
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| void writeToState(const Assignment assignment, std::unique_ptr<AtomicState> &state) override { | ||
| state->crtc(assignment.object->id())->active = assignment.intValue; | ||
| } |
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Unrelated change? Seems that this function is never called.
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While unused now, I have some patches to drivers that make this necessary as some piece of software relied on this property.
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Then this function should be added in a future PR that also adds consumers.
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Okay, the handle-related issue is solved now, but now I don't understand why we need _primeBufferMap at all. The only place where this is read is importBufferObject(). Can't we just adjust importBufferObject() to either return the existing handle (that we get via getHandle()) or create a new handle (via createHandle()), without looking at _primeBufferMap? Or am I missing something?
The remainder of the PR now looks good to me.
Co-authored-by: Kacper Słomiński <kacper.slominski72@gmail.com>
This commit adds support for the `PRIME_HANDLE_TO_FD` and `PRIME_FD_TO_HANDLE` ioctls. These convert between a DRM handle (as used for the MAP_DUMB ioctl) and a fd, which supports the regular operations, including being sent over a UNIX socket and being `dup`ed. This is achieved by managing the shared buffers at the device level by being exported and imported. The shared buffers are identified by the credentials (a unique identifier) of the passthrough lane servicing the file operations, as fds are obviously not stable across threads.
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This is rough code for making the PRIME ioctls work for sway. The code is not optimal and the naming is weird, but I couldn't come up with something better.
Posting as draft, as I don't expect this to survive review unchanged.
mlibc counterpart is managarm/mlibc#367.