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Mon, 29 Jun 2026 04:39:03 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: ApSqBjiSqQZ- Date: Mon, 29 Jun 2026 10:38:16 +0200 From: "Arnd Bergmann" To: "Juergen Gross" , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "linux-edac@vger.kernel.org" , x86@kernel.org, linux-acpi@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-pci@vger.kernel.org, virtualization@lists.linux.dev, linux-ide@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-crypto@vger.kernel.org, "open list:GPIO SUBSYSTEM" , linux-hyperv@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mtd@lists.infradead.org, platform-driver-x86@vger.kernel.org Cc: "Rafael J . Wysocki" , "Daniel Lezcano" , "Zhang Rui" , "lukasz.luba@arm.com" , "Jason Baron" , "Borislav Petkov" , "Tony Luck" , "Yazen Ghannam" , "Len Brown" , "Pavel Machek" , "Thomas Gleixner" , "Ingo Molnar" , "Dave Hansen" , "H. Peter Anvin" , "Sean Christopherson" , "Paolo Bonzini" , "Kirill A. Shutemov" , "Rick Edgecombe" , "Pu Wen" , "Bjorn Helgaas" , "Ajay Kaher" , "Alexey Makhalov" , "Broadcom internal kernel review list" , "Viresh Kumar" , "Reinette Chatre" , "Dave Martin" , "James Morse" , "Babu Moger" , "Tony W Wang-oc" , "Damien Le Moal" , "Niklas Cassel" , "Dave Airlie" , "Helge Deller" , linux-geode@lists.infradead.org, "Olivia Mackall" , "Herbert Xu" , "Linus Walleij" , "Bartosz Golaszewski" , "Greg Kroah-Hartman" , "K. Y. Srinivasan" , "Haiyang Zhang" , "Wei Liu" , "Dexuan Cui" , "Long Li" , "Guenter Roeck" , "Peter Zijlstra" , "Arnaldo Carvalho de Melo" , "Namhyung Kim" , "Mark Rutland" , "Alexander Shishkin" , "Jiri Olsa" , "Ian Rogers" , "Adrian Hunter" , "James Clark" , "Josh Poimboeuf" , "Pawan Gupta" , "Vitaly Kuznetsov" , "Andy Lutomirski" , "Boris Ostrovsky" , "Huang Rui" , "Mario Limonciello" , "Perry Yuan" , "K Prateek Nayak" , "srinivas.pandruvada@linux.intel.com" , "Artem Bityutskiy" , "Artem Bityutskiy" , "Miquel Raynal" , "Richard Weinberger" , "Vignesh Raghavendra" , "Ashok Raj" , "Hans de Goede" , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , "Rajneesh Bhardwaj" , "David E Box" , xen-devel@lists.xenproject.org Message-Id: In-Reply-To: <9acced19-573d-4923-9329-8be408d2e555@suse.com> References: <20260629060526.3638272-1-jgross@suse.com> <7332feff-2649-496c-8e49-b0a19eb54a32@app.fastmail.com> <9acced19-573d-4923-9329-8be408d2e555@suse.com> Subject: Re: [PATCH 00/32] x86/msr: Drop 32-bit MSR interfaces Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Mon, Jun 29, 2026, at 10:15, J=C3=BCrgen Gro=C3=9F wrote: > On 29.06.26 10:06, Arnd Bergmann wrote: >> On Mon, Jun 29, 2026, at 09:01, J=C3=BCrgen Gro=C3=9F wrote: >>> On 29.06.26 08:52, Arnd Bergmann wrote: >>>> On Mon, Jun 29, 2026, at 08:04, Juergen Gross wrote: >>>> >>>> I assume this is fine, but since you don't mention it explicitly he= re, >>>> please clarify what this means for 32-bit CPUs without the rdmsrq >>>> instruction. Those will continue using the same instructions as bef= ore >>>> and just change the calling conventions, right? >>> >>> Yes. I thought this would be clear from the following: >>> >>> - They are based on primitives using 64-bit sized values anyway. >>=20 >> Right, that was my reading of it as well, but it's not entirely >> clear when the function name is the same as the mnemonic of an >> instruction that only exists on newer CPUs and the later patch > > There is no RDMSRQ instruction on any x86 CPU. Are you mixing this up = with > WRMSRNS/RDMSR using an immediate for addressing the MSR? Yes, I was just confused about the exact definition here and assumed the single-register output version was actually called rdmsrq. Arnd