From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outpost1.zedat.fu-berlin.de (outpost1.zedat.fu-berlin.de [130.133.4.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B19C3501F4E; Thu, 15 Oct 2026 09:36:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=130.133.4.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792057014; cv=none; b=DztQQUi7z4R7yJ3BdXxJRQZhJaeWmi/QqOMR2YF+/ucIDIb/4zmrq603tLXPK54lGDapcEYnC/BhKmD6u9G5WQhFeSMtwPQEh30tU9lbw68yB+p8zPCEPYYRV8+Cl8Lg7P1NEGU3ovTOmVMRhwf3jsrBu8A6aGWUfLMjGF67ees= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792057014; c=relaxed/simple; bh=5sqpNvof8MuHAPKLoe4K3oHc6awGsxJxQTGEKdfGsog=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=uZ6XjSt2fb1eLJcgT/Tn79Oz3UN86VajM59jIscflljPlkbtuCgu+uslKf/P4be3JyN/TzhK0x/5hoBXSom/0ws6GOzgOBQzkWMM4Tlzx+wXeS+gmD9+tAYJSvs3VdpYLChDs+NsbvP0os1Iyc4Y4y8oDKH7saeNcwtPDOU+2kM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de; spf=pass smtp.mailfrom=zedat.fu-berlin.de; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b=GIWUVXCm; arc=none smtp.client-ip=130.133.4.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zedat.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b="GIWUVXCm" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fu-berlin.de; s=fub01; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:From: Reply-To:Subject:Date:Message-ID:To:Cc:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:In-Reply-To: References; bh=x3wN+n+RLe6LYEfdS3KbfapbSOfa7ZrNdty2cZl3Zow=; t=1792057008; x=1792661808; b=GIWUVXCm9+dzPanYLm0Sk81nRpdGAPrHkiPaNfOcbAzz4iLQYhzaEGg9r2Hdf poHLXuyzmxRBSuXB+og9Zh1QCsek8qaWOdCRTk975uxPxCQgifVx1s8YK5iQJ0qt2PWCIco1+1gNf mETtYUDG+9GVddA0sLaIcx/PL91y/temaLtzstJvIQOcXWhFpoH2hNQL02CTWGW4gihJ+u8okmSjC WX4P5YicCreS0XC6jsB1IQE5zv3fTNi4mZxdHRwgPAEGFhEdFXY17V59IOV+XH9xzaBhzjdBokIIj fhVKIUaEbSFdnIa+yS7MRcDTQVP/RCgxLU2xhyzwHtHZR4jsuQ==; Received: from inpost2.zedat.fu-berlin.de ([130.133.4.69]) by outpost.zedat.fu-berlin.de (Exim 4.100) with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1xHHtF-000000035io-033M; Thu, 15 Oct 2026 11:36:45 +0200 Received: from p5b13a90a.dip0.t-ipconnect.de ([91.19.169.10] helo=[192.168.178.61]) by inpost2.zedat.fu-berlin.de (Exim 4.100) with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1xHHtE-00000003Fwi-3HCV; Thu, 15 Oct 2026 11:36:44 +0200 Message-ID: <8553d8909cc477ae1cb0fc1a071ffe579a8ee40a.camel@physik.fu-berlin.de> Subject: Re: [PATCH 4/4] sparc32: add the sparc_atomic_cmpxchg_32 system call From: John Paul Adrian Glaubitz To: Arnd Bergmann , Ramin Moussavi , Andreas Larsson , "David S . Miller" Cc: Thomas Gleixner , Peter Zijlstra , Guenter Roeck , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 15 Oct 2026 11:36:43 +0200 In-Reply-To: <026b6108-f25b-47a1-a4e0-fa7717d926d4@app.fastmail.com> References: <20261015085545.3246951-1-ramin.moussavi@yacoub.de> <20261015085545.3246951-5-ramin.moussavi@yacoub.de> <026b6108-f25b-47a1-a4e0-fa7717d926d4@app.fastmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Original-Sender: glaubitz@physik.fu-berlin.de X-ZEDAT-Hint: PO On Thu, 2026-10-15 at 11:21 +0200, Arnd Bergmann wrote: > On Thu, Oct 15, 2026, at 10:55, Ramin Moussavi wrote: > > User space built for v8 has no compare-and-swap. C libraries emulate it > > with ldstub locks of their own, and those have two problems the kernel > > cannot see. They are not async-signal-safe: a handler that reaches an > > atomic while the code it interrupted holds the lock spins forever. And > > the kernel does not know them: FUTEX_WAKE_OP and robust futexes write > > the same words without taking those locks. >=20 > As far as I know, the baseline in sparc32 glibc has been leon3 or > sparcv9 for a long time, so CASA should always be available. >=20 > Any remaining sun4m users are on an ancient userspace with a > pre-futex glibc. There are several contributors that are trying to revive Linux on pre-Leon 32-bit SPARC machines. Recently, Magnus Lindholm made some contributions to be able to boot a modern kernel on his old SuperSPARC workstation [1]. The changes have already been merged into Andreas' tree for linux-next [2]. Adrian > [1] https://lore.kernel.org/all/20261007174128.959307-1-linmag7@gmail.com= / > [2] https://git.kernel.org/pub/scm/linux/kernel/git/alarsson/linux-sparc.= git/log/?h=3Dfor-next --=20 .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913