[lkml]   [2018]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] docs/memory-barriers.txt: Fix broken DMA vs MMIO ordering example
On Wed, Mar 28, 2018 at 6:02 AM, Sinan Kaya <> wrote:
> +linux-ia64
> Does IA64 follow this requirement? If not, is implementation planned?
> "no wmb() before writel()"
> Linus asked us to get rid of wmb() in front of writel() for UC memory.
> Just checking that we are not breaking anything for IA64.

We should be OK on ia64, writel() uses a cast to:

*(volatile unsigned int __force *)

which the compiler takes as a request to use a "st4.rel" instruction
(meaning "store with release semantics"). So the value stored will
be visible to anything that follows.


 \ /
  Last update: 2018-03-28 19:57    [W:0.041 / U:1.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site