From: "Arnd Bergmann" <arnd@arndb.de>
To: "Paul E. McKenney" <paulmck@kernel.org>,
"John Paul Adrian Glaubitz" <glaubitz@physik.fu-berlin.de>
Cc: Linux-Arch <linux-arch@vger.kernel.org>,
linux-kernel@vger.kernel.org, "Marco Elver" <elver@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Peter Zijlstra" <peterz@infradead.org>,
"Doug Anderson" <dianders@chromium.org>,
"Petr Mladek" <pmladek@suse.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
kernel-team@meta.com, "Andi Shyti" <andi.shyti@linux.intel.com>,
"Palmer Dabbelt" <palmer@rivosinc.com>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
linux-sh@vger.kernel.org,
"Alexander Viro" <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg
Date: Thu, 02 May 2024 23:50:21 +0200 [thread overview]
Message-ID: <989112a7-c12a-40be-9c0d-e516880380ad@app.fastmail.com> (raw)
In-Reply-To: <9a4e1928-961d-43af-9951-71786b97062a@paulmck-laptop>
On Thu, May 2, 2024, at 15:33, Paul E. McKenney wrote:
> On Thu, May 02, 2024 at 07:11:52AM +0200, John Paul Adrian Glaubitz wrote:
>> On Wed, 2024-05-01 at 22:06 -0700, Paul E. McKenney wrote:
>> > > Does cmpxchg_emu_u8() have any advantages over the native xchg_u8()?
>> >
>> > That would be 8-bit xchg() rather than 8-byte cmpxchg(), correct?
>>
>> Indeed. I realized this after sending my reply.
>
> So this one-byte-only series affects only Alpha systems lacking
> single-byte load/store instructions. If I understand correctly, Alpha
> 21164A (EV56) and later *do* have single-byte load/store instructions,
> and thus are still just fine. In fact, it looks like EV56 also has
> two-byte load/store instructions, and so would have been OK with
> the original one-/two-byte RFC series.
Correct, the only other architecture I'm aware of that is missing
16-bit load/store entirely is ARMv3.
> Arnd will not be shy about correcting me if I am wrong. ;-)
I'll take this as a reminder to send out my EV4/EV5 removal
series. I've merged my patches with Al's bugfixes and rebased
all on top of 6.9-rc now. It's a bit late now, so I'll
send this tomorrow:
https://git.kernel.org/pub/scm/linux/kernel/garch/alpha/include/asm/cmpxchg.hit/arnd/asm-generic.git/log/?h=alpha-cleanup-6.9
Arnd
next prev parent reply other threads:[~2024-05-02 21:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <b67e79d4-06cb-4a45-a906-b9e0fbae22c5@paulmck-laptop>
2024-05-01 23:01 ` [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-02 4:52 ` John Paul Adrian Glaubitz
2024-05-02 5:06 ` Paul E. McKenney
2024-05-02 5:11 ` John Paul Adrian Glaubitz
2024-05-02 13:33 ` Paul E. McKenney
2024-05-02 20:53 ` Al Viro
2024-05-02 21:01 ` alpha cmpxchg.h (was Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg) Al Viro
2024-05-02 22:16 ` Linus Torvalds
2024-05-02 21:18 ` [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-02 22:07 ` Al Viro
2024-05-02 23:12 ` Paul E. McKenney
2024-05-02 23:24 ` Al Viro
2024-05-02 23:45 ` Paul E. McKenney
2024-05-02 23:32 ` Linus Torvalds
2024-05-03 0:16 ` Paul E. McKenney
2024-05-02 21:50 ` Arnd Bergmann [this message]
2024-05-02 5:42 ` D. Jeff Dionne
2024-05-02 11:30 ` Arnd Bergmann
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