• Will Deacon's avatar
    docs/memory-barriers.txt: Enforce heavy ordering for port I/O accesses · f256ade3
    Will Deacon authored
    David Laight explains:
      | A long time ago there was a document from Intel that said that
      | inb/outb weren't necessarily synchronised wrt memory accesses.
      | (Might be P-pro era). However no processors actually behaved that
      | way and more recent docs say that inb/outb are fully ordered.
    This also reflects the situation on other architectures, the the port
    accessor macros tend to be implemented in terms of readX/writeX.
    Update Documentation/memory-barriers.txt to reflect reality.
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: David Laight <David.Laight@ACULAB.COM>
    Cc: Alan Stern <stern@rowland.harvard.edu>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: <linux-arch@vger.kernel.org>
    Cc: <linux-doc@vger.kernel.org>
    Cc: <linux-kernel@vger.kernel.org>
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
memory-barriers.txt 115 KB