Merge drm/drm-next into drm-intel-next (b2eb7d71) · Commits · EulixOS / Software / Kernel

Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers

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		What: /sys/kernel/dmabuf/buffers
		Date: May 2021
		KernelVersion: v5.13
		Contact: Hridya Valsaraju <hridya@google.com>
		Description: The /sys/kernel/dmabuf/buffers directory contains a
		snapshot of the internal state of every DMA-BUF.
		/sys/kernel/dmabuf/buffers/<inode_number> will contain the
		statistics for the DMA-BUF with the unique inode number
		<inode_number>
		Users: kernel memory tuning/debugging tools

		What: /sys/kernel/dmabuf/buffers/<inode_number>/exporter_name
		Date: May 2021
		KernelVersion: v5.13
		Contact: Hridya Valsaraju <hridya@google.com>
		Description: This file is read-only and contains the name of the exporter of
		the DMA-BUF.

		What: /sys/kernel/dmabuf/buffers/<inode_number>/size
		Date: May 2021
		KernelVersion: v5.13
		Contact: Hridya Valsaraju <hridya@google.com>
		Description: This file is read-only and specifies the size of the DMA-BUF in
		bytes.

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		@@ -33,6 +33,13 @@ Description:
		frequency adjustment value (a positive integer) in
		parts per billion.

		What: /sys/class/ptp/ptpN/max_vclocks
		Date: May 2021
		Contact: Yangbo Lu <yangbo.lu@nxp.com>
		Description:
		This file contains the maximum number of ptp vclocks.
		Write integer to re-configure it.

		What: /sys/class/ptp/ptpN/n_alarms
		Date: September 2010
		Contact: Richard Cochran <richardcochran@gmail.com>
		@@ -61,6 +68,19 @@ Description:
		This file contains the number of programmable pins
		offered by the PTP hardware clock.

		What: /sys/class/ptp/ptpN/n_vclocks
		Date: May 2021
		Contact: Yangbo Lu <yangbo.lu@nxp.com>
		Description:
		This file contains the number of virtual PTP clocks in
		use. By default, the value is 0 meaning that only the
		physical clock is in use. Setting the value creates
		the corresponding number of virtual clocks and causes
		the physical clock to become free running. Setting the
		value back to 0 deletes the virtual clocks and
		switches the physical clock back to normal, adjustable
		operation.

		What: /sys/class/ptp/ptpN/pins
		Date: March 2014
		Contact: Richard Cochran <richardcochran@gmail.com>

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		@@ -45,8 +45,9 @@ how the user addresses are used by the kernel:

		1. User addresses not accessed by the kernel but used for address space
		management (e.g. ``mprotect()``, ``madvise()``). The use of valid
		tagged pointers in this context is allowed with the exception of
		``brk()``, ``mmap()`` and the ``new_address`` argument to
		tagged pointers in this context is allowed with these exceptions:

		- ``brk()``, ``mmap()`` and the ``new_address`` argument to
		``mremap()`` as these have the potential to alias with existing
		user addresses.

		@@ -54,6 +55,15 @@ how the user addresses are used by the kernel:
		incorrectly accept valid tagged pointers for the ``brk()``,
		``mmap()`` and ``mremap()`` system calls.

		- The ``range.start``, ``start`` and ``dst`` arguments to the
		``UFFDIO_*`` ``ioctl()``s used on a file descriptor obtained from
		``userfaultfd()``, as fault addresses subsequently obtained by reading
		the file descriptor will be untagged, which may otherwise confuse
		tag-unaware programs.

		NOTE: This behaviour changed in v5.14 and so some earlier kernels may
		incorrectly accept valid tagged pointers for this system call.

		2. User addresses accessed by the kernel (e.g. ``write()``). This ABI
		relaxation is disabled by default and the application thread needs to
		explicitly enable it via ``prctl()`` as follows:

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		@@ -86,19 +86,7 @@ Generating code coverage reports under UML
		.. note::
		TODO(brendanhiggins@google.com): There are various issues with UML and
		versions of gcc 7 and up. You're likely to run into missing ``.gcda``
		files or compile errors. We know one `faulty GCC commit
		<https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21645f9d>`_
		but not how we'd go about getting this fixed. The compile errors still
		need some investigation.

		.. note::
		TODO(brendanhiggins@google.com): for recent versions of Linux
		(5.10-5.12, maybe earlier), there's a bug with gcov counters not being
		flushed in UML. This translates to very low (<1%) reported coverage. This is
		related to the above issue and can be worked around by replacing the
		one call to ``uml_abort()`` (it's in ``os_dump_core()``) with a plain
		``exit()``.

		files or compile errors.

		This is different from the "normal" way of getting coverage information that is
		documented in Documentation/dev-tools/gcov.rst.

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