From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3CB97FD5307 for ; Fri, 27 Feb 2026 07:40:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Date:Cc:To:From :Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=V6J0SL9RsbUQWhN8iu+ey8pLnEs4VtLYMczUYtzIoAc=; b=llRPtZjEocy5kgWE/ZHmVlMq14 bfy6gYzxGcGAqdaQm0atVAt68tNoVqIL7vb/VhUeUWMejGDzdiAWWX5Y6/IqgvheTRpCUVca4pZAZ FyQo0l2R9vodwnc/F1SRKYfFCECl9IWJ2GPeqNM0s/5VDsT9N+F6JFL65Zw3Y8RrGQLRc39w29wiK Z1ZIhfj4TZ+hTdIwBZi9q5lEQppw3bbAg9nY6N+NdEbvZh/XSXfR8Eh+YlkAh3AuvbAvYLED7M3jl l0XgTeovIa37avjvAGTpJV/CfI1nhF1OjiJHpo+benL/qWG6qSD6JFkuquowZyyoGPCKZBtyBt1rj fEWpPQiw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vvsSp-00000007uDh-16Fw; Fri, 27 Feb 2026 07:40:43 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:242:246e::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vvsSm-00000007uCN-04HB; Fri, 27 Feb 2026 07:40:41 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=V6J0SL9RsbUQWhN8iu+ey8pLnEs4VtLYMczUYtzIoAc=; t=1772178039; x=1773387639; b=ocma0MZIuXziW7lVh/1E1Go3lVZm87iiHWwbamFyj9KsjK2 ihnkU0Xkjll+4MCeX6dkwdr7neACMPj1Vu7HQhfI24NqjBGFJGCzf9CFfNz3L8UAEXWpLvDXw5h3q HkPk3AUrl0JcsVIcbtBpTP/6Aife6hS0USV6ITM/HpUwgdNr1k1sK6OYhTATIkVgc/km7CpMGDazi Y5J5wlYaL5p5OH+nFQyysOTLMBaHIvV2pf/+YSBpXqi5lIjTHh2ojJmlrMpeye5W3u3pMaYzPd03e AXrU831528yWeev6QzQuJ/b+s9hs0kgENclbwfzC8lrpYO5gzKOCnblALSiivpYw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1vvsRx-00000003Eus-2oGQ; Fri, 27 Feb 2026 08:39:49 +0100 Message-ID: <4f69d30f952bc374e69f44786f662886c30058e9.camel@sipsolutions.net> Subject: Re: [PATCH 03/25] um/xor: don't override XOR_SELECT_TEMPLATE From: Johannes Berg To: Richard Weinberger , hch Cc: Andrew Morton , Richard Henderson , Matt Turner , Magnus Lindholm , Russell King , Catalin Marinas , will , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , davem , Andreas Larsson , anton ivanov , Thomas Gleixner , mingo , bp , dave hansen , x86 , hpa , Herbert Xu , dan j williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , linux-alpha , linux-kernel , linux-arm-kernel , loongarch , linuxppc-dev , linux-riscv , linux-s390 , sparclinux , linux-um , Linux Crypto Mailing List , linux-btrfs , linux-arch , linux-raid , Ard Biesheuvel Date: Fri, 27 Feb 2026 08:39:47 +0100 In-Reply-To: <445921547.2198.1772142326749.JavaMail.zimbra@nod.at> References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-4-hch@lst.de> <445921547.2198.1772142326749.JavaMail.zimbra@nod.at> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) MIME-Version: 1.0 X-malware-bazaar: not-scanned X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260226_234040_079165_9AC218B7 X-CRM114-Status: GOOD ( 14.21 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On Thu, 2026-02-26 at 22:45 +0100, Richard Weinberger wrote: > ----- Urspr=C3=BCngliche Mail ----- > > Von: "hch" > > XOR_SELECT_TEMPLATE is only ever called with a NULL argument, so all th= e > > ifdef'ery doesn't do anything. With our without this, the time travel > > mode should work fine on CPUs that support AVX2, as the AVX2 > > implementation is forced in this case, and won't work otherwise. >=20 > IIRC Johannes added XOR_SELECT_TEMPLATE() here to skip > the template selection logic because it didn't work with time travel mode= . >=20 > Johannes, can you please test whether this change does not break > time travel mode? It does work, even if it reports nonsense (as you'd expect): xor: measuring software checksum speed prefetch64-sse : 12816000 MB/sec sse : 12816000 MB/sec xor: using function: prefetch64-sse (12816000 MB/sec) I think it works now because the loop is using ktime and is bounded by REPS, since commit c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking"). The RAID speed select still hangs, but we've gotten that removed via Kconfig, so that's already handled. Perhaps raid6_choose_gen() should use a similar algorithm? But for UML it doesn't really matter since CONFIG_RAID6_PQ_BENCHMARK exists. As far as AVX2 is concerned, yeah, I guess that was a bug, but evidently nobody (who configured time-travel) ever cared - what _did_ matter though in practice is that the boot not get stuck entirely... Two completely separate issues. johannes