Re: [GIT PULL] Add two-byte cmpxchg emulation function for v7.4

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hello Paul,

On Tue, 2026-10-20 at 12:14 -0700, Paul E. McKenney wrote:
> On Tue, Oct 20, 2026 at 08:48:32PM +0200, John Paul Adrian Glaubitz wrote:
> > Hi Paul,
> > 
> > On Fri, 2026-10-16 at 20:51 -0700, Paul E. McKenney wrote:
> > > However, it sadly does not permit easy implementation of all algorithms
> > > needing on two-byte atomic operations because there are some systems still
> > > supported by Linux that do not have native two-byte store instructions.
> > > There is reason to believe that these systems will soon no longer be
> > > supported by Linux.
> > 
> > Since this paragraph has produced a headline today [1], would you mind
> > clarifying what you meant here? What architectures are you talking about?
> 
> The important word in the second paragraph quoted by the article is
> "systems", which is not "architectures".   To its credit, the article
> keeps this straight, but not so much the comments.
> 
> And here is Arnd Bergmann's patch that started this:
> 
> https://lore.kernel.org/all/20260908152808.3928630-4-arnd@kernel.org/
> 
> The system Arnd calls out is the Acorn Risc PC, which is one member of the
> Arm family.  So not an entire architecture, but rather just a particular
> implementation of an architecture, and an old one at that.  Not only
> that, but if I remember correctly, Arnd got considerable pushback,
> so I am not sure that his support-removal patch is going in just yet,
> as in I do not yet see it in -next.
> 
> Please feel free to add this as a comment to the article, as the site
> is not permitting me to do so.  I have added their feedback email on
> CC in case that helps, and in the hope that my doing so does not unduly
> annoy them.

Thanks a lot for the clarification, much appreciated!

Relieved,
Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
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