On 26/01/2026 18:34, Konstantin Belousov wrote:
On Mon, Jan 26, 2026 at 03:57:45PM +0000, Marius Strobl wrote:
The branch main has been updated by marius:
URL:
https://cgit.FreeBSD.org/src/commit/?id=e769bc77184312b6137a9b180c97b87c0760b849
commit e769bc77184312b6137a9b180c97b87c0760b849
Author: Marius Strobl <[email protected]>
AuthorDate: 2026-01-26 13:58:57 +0000
Commit: Marius Strobl <[email protected]>
CommitDate: 2026-01-26 15:54:48 +0000
sym(4): Employ memory barriers also on x86
In an MP world, it doesn't hold that x86 requires no memory barriers.
It does hold. x86 is much more strongly ordered than all other arches
we currently support.
That said, the use of the barriers in drivers is usually not justified
(I did not looked at this specific case).
Even if needed, please stop using rmb/wmb etc. Use atomic_thread_fence()
of appropriate kind, see atomic(9). Then on x86 it does the right thing.
I understand that this advice is for the "normal" memory access model.
But does it apply to "special" memory? E.g., to memory-based communication with
devices?
--
Andriy Gapon
