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Fri, 13 Dec 2024 03:04:01 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 13 Dec 2024 09:03:30 +0100 From: "Arnd Bergmann" To: "A. Wilcox" , "Arnd Bergmann" Cc: kvm@vger.kernel.org, "Thomas Bogendoerfer" , "Huacai Chen" , "Jiaxun Yang" , "Michael Ellerman" , "Nicholas Piggin" , "Christophe Leroy" , "Naveen N Rao" , "Madhavan Srinivasan" , "Alexander Graf" , "Crystal Wood" , "Anup Patel" , "Atish Patra" , "Paul Walmsley" , "Palmer Dabbelt" , "Albert Ou" , "Sean Christopherson" , "Paolo Bonzini" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , x86@kernel.org, "H. Peter Anvin" , "Vitaly Kuznetsov" , "David Woodhouse" , "Paul Durrant" , "Marc Zyngier" , linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org Message-Id: <6e971322-8b21-4d73-922c-a6032c6fe9bd@app.fastmail.com> In-Reply-To: <35E5C2A3-94AC-446B-A0A1-84B043DBC890@Wilcox-Tech.com> References: <20241212125516.467123-1-arnd@kernel.org> <35E5C2A3-94AC-446B-A0A1-84B043DBC890@Wilcox-Tech.com> Subject: Re: [RFC 0/5] KVM: drop 32-bit host support on all architectures Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, Dec 13, 2024, at 04:51, A. Wilcox wrote: > On Dec 12, 2024, at 6:55=E2=80=AFAM, Arnd Bergmann w= rote: >> From: Arnd Bergmann >>=20 >> I submitted a patch to remove KVM support for x86-32 hosts earlier >> this month, but there were still concerns that this might be useful f= or >> testing 32-bit host in general, as that remains supported on three ot= her >> architectures. I have gone through those three now and prepared simil= ar >> patches, as all of them seem to be equally obsolete. >>=20 >> Support for 32-bit KVM host on Arm hardware was dropped back in 2020 >> because of lack of users, despite Cortex-A7/A15/A17 based SoCs being >> much more widely deployed than the other virtualization capable 32-bit >> CPUs (Intel Core Duo/Silverthorne, PowerPC e300/e500/e600, MIPS P5600) >> combined. > > > I do use 32-bit KVM on a Core Duo =E2=80=9CYonah=E2=80=9D and a Power = Mac G4 (MDD), for > purposes of bisecting kernel issues without having to reboot the host > machine (when it can be duplicated in a KVM environment). > > I suppose it would still be possible to run the hosts on 6.12 LTS for > some time with newer guests, but it would be unfortunate. Would it be an option for you to just test those kernels on 64-bit machines? I assume you prefer to do native builds on 32-bit hardware because that fits your workflow, but once you get into debugging in a virtual machine, the results should generally be the same when building and running on a 64-bit host for both x86-32 and ppc32-classic, right? Arnd