On Wed, 2015-21-10 at 05:03:14 UTC, Paul Mackerras wrote: > This reverts commit 9678cdaae93932473f696fdea5debf3eee1e1260 because > the original commit had multiple, partly self-cancelling bugs, that > could cause occasional memory corruption. In fact the logmpp instruction > was using register r0 as the source of the buffer address and operation > code, and depending on what was in r0, it would either do nothing or > corrupt the 64k page pointed to by r0. The logmpp instruction encoding > and the operation code definitions could be corrected, but then there is > the problem that there is no clearly defined way to know when the > hardware has finished writing to the buffer. The original commit > attempted to work around this by aborting the write-out before starting > the prefetch, but this is ineffective in the case where the virtual > core is now executing on a different physical core from the one where > the write-out was initiated. > > These problems plus advice from the hardware designers not to use the > function (since the measured performance improvement from using the > feature was actually mostly negative), mean that reverting the code is > the best option. > > Signed-off-by: Paul Mackerras <pau...@samba.org>
Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/23316316c1af0677a041c81f cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
