Re: [PATCH v2 4/5] powerpc: kvm: drop 32-bit book3s

From: "J. Neuschäfer" <j.neuschaefer@gmx.net>
To: "A. Wilcox" <AWilcox@wilcox-tech.com>
Cc: Arnd Bergmann <arnd@kernel.org>,
	kvm@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Huacai Chen <chenhuacai@kernel.org>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Naveen N Rao <naveen@kernel.org>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Alexander Graf <graf@amazon.com>,
	Crystal Wood <crwood@redhat.com>,
	Anup Patel <anup@brainfault.org>,
	Atish Patra <atishp@atishpatra.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Paul Durrant <paul@xen.org>, Marc Zyngier <maz@kernel.org>,
	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
Subject: Re: [PATCH v2 4/5] powerpc: kvm: drop 32-bit book3s
Date: Sun, 2 Feb 2025 22:33:36 +0100	[thread overview]
Message-ID: <Z5_ksID8Gv_Tg5F7@probook> (raw)
In-Reply-To: <9B9E07F0-3373-4F59-BE4C-E6C425B3C36D@Wilcox-Tech.com>

On Sat, Dec 21, 2024 at 08:13:12PM -0600, A. Wilcox wrote:
> On Dec 21, 2024, at 3:42 PM, Arnd Bergmann <arnd@kernel.org> wrote:
> >
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Support for KVM on 32-bit Book III-s implementations was added in 2010
> > and supports PowerMac, CHRP, and embedded platforms using the Freescale G4
> > (mpc74xx), e300 (mpc83xx) and e600 (mpc86xx) CPUs from 2003 to 2009.
> >
> > Earlier 603/604/750 machines might work but would be even more limited
> > by their available memory.
> >
> > The only likely users of KVM on any of these were the final Apple
> > PowerMac/PowerBook/iBook G4 models with 2GB of RAM that were at the high
> > end 20 years ago but are just as obsolete as their x86-32 counterparts.
> > The code has been orphaned since 2023.
> >
> > There is still a need to support 32-bit guests in order to better
> > debug problems on ppc32 kernels. This should work in theory on both
> > 64-bit booke and on 64-bit book3s hosts, but it would be good to
> > confirm that this is still the case before the known working option
> > gets removed.
[...]
> That said, I would like to keep the support alive for more than just
> ppc32 kernel testing.  There are plenty of Power Macs with enough
> memory to run some environments within KVM.  Adélie’s new release
> boots a full XFCE desktop in under 300 MB RAM, so even a 1 GB machine
> has enough memory to run AmigaOS, Mac OS 9, or another XFCE in KVM.

FWIW, I second this. I do intend to get KVM to run on my e300-based
board for some relatively light guests such as Mac OS 9. I suspect I
won't be able to contribute much to the maintenance, though.

Best regards,
J. Neuschäfer

-- 
kvm-riscv mailing list
kvm-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kvm-riscv