From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To: Arnd Bergmann <arnd@arndb.de>,
Ramin Moussavi <ramin.moussavi@yacoub.de>,
Andreas Larsson <andreas@gaisler.com>,
"David S . Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Guenter Roeck <linux@roeck-us.net>,
sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org,
Imre Kaloz <kaloz@kernel.org>
Subject: Re: [PATCH 3/4] sparc32: implement futex atomics, with casa detected at run time
Date: Thu, 15 Oct 2026 11:28:47 +0200 [thread overview]
Message-ID: <ed61723a01eeeb2e94306de3be3a363974b984fb.camel@physik.fu-berlin.de> (raw)
In-Reply-To: <7334b77c-2ec7-4678-8296-f187e0304f49@app.fastmail.com>
On Thu, 2026-10-15 at 11:23 +0200, Arnd Bergmann wrote:
> On Thu, Oct 15, 2026, at 10:55, Ramin Moussavi wrote:
> > sparc32 has no futex_atomic_cmpxchg_inatomic() or
> > arch_futex_atomic_op_inuser() of its own. The generic versions only
> > work on UP, so FUTEX depends on !(SPARC32 && SMP) and an SMP kernel
> > has no futexes at all; NPTL cannot run on it.
>
> I believe there are existing patches for LEON with CASA that
> should just be merged, I would not worry about supporting broken
> CPUs that never had this.
I think you mean the series by Imre Kaloz [1]? If yes, he actually
implements CASA emulation unless I'm missing something.
Adrian
> [1] https://lore.kernel.org/sparclinux/20260927005821.8369-1-kaloz@kernel.org/
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
next prev parent reply other threads:[~2026-10-15 9:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-15 8:55 [PATCH 0/4] sparc32: SMP fixes, futexes on SMP, and a cmpxchg system call Ramin Moussavi
2026-10-15 8:55 ` [PATCH 1/4] sparc32: keep PIL raised until the IRQ frame is gone Ramin Moussavi
2026-10-15 10:48 ` Magnus Lindholm
2026-10-15 12:20 ` Andreas Larsson
2026-10-15 8:55 ` [PATCH 2/4] sparc32: wait for secondary CPUs by time, not by loop count Ramin Moussavi
2026-10-15 9:09 ` Arnd Bergmann
2026-10-15 13:43 ` Ramin Moussavi
2026-10-15 8:55 ` [PATCH 3/4] sparc32: implement futex atomics, with casa detected at run time Ramin Moussavi
2026-10-15 9:23 ` Arnd Bergmann
2026-10-15 9:28 ` John Paul Adrian Glaubitz [this message]
2026-10-15 9:45 ` Arnd Bergmann
2026-10-15 8:55 ` [PATCH 4/4] sparc32: add the sparc_atomic_cmpxchg_32 system call Ramin Moussavi
2026-10-15 9:21 ` Arnd Bergmann
2026-10-15 9:36 ` John Paul Adrian Glaubitz
2026-10-15 9:36 ` [PATCH 0/4] sparc32: SMP fixes, futexes on SMP, and a cmpxchg " Magnus Lindholm
2026-10-15 14:15 ` Ramin Moussavi
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