From: "Russell King (Oracle)" <linux@armlinux•org.uk>
To: Jason Gunthorpe <jgg@nvidia•com>
Cc: Arnd Bergmann <arnd@arndb•de>, Arnd Bergmann <arnd@kernel•org>,
linux-mm@kvack•org, Andrew Morton <akpm@linux-foundation•org>,
Andreas Larsson <andreas@gaisler•com>,
Christophe Leroy <chleroy@kernel•org>,
Dave Hansen <dave.hansen@linux•intel.com>,
Linus Walleij <linus.walleij@linaro•org>,
Matthew Wilcox <willy@infradead•org>,
Richard Weinberger <richard@nod•at>,
linux-arm-kernel@lists•infradead.org,
linux-fsdevel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
x86@kernel•org
Subject: Re: [PATCH 3/4] ARM: remove support for highmem on VIVT
Date: Fri, 2 Jan 2026 12:12:32 +0000 [thread overview]
Message-ID: <aVe2MH0TUsobPaKL@shell.armlinux.org.uk> (raw)
In-Reply-To: <aUtPRFdbpSQ20eOx@nvidia.com>
On Tue, Dec 23, 2025 at 10:26:12PM -0400, Jason Gunthorpe wrote:
> On Fri, Dec 19, 2025 at 09:34:33PM +0100, Arnd Bergmann wrote:
> > On Fri, Dec 19, 2025, at 18:14, Jason Gunthorpe wrote:
> > > On Fri, Dec 19, 2025 at 05:15:58PM +0100, Arnd Bergmann wrote:
> > >> arch/arm/Kconfig | 1 +
> > >> arch/arm/configs/gemini_defconfig | 1 -
> > >> arch/arm/configs/multi_v5_defconfig | 1 -
> > >> arch/arm/configs/mvebu_v5_defconfig | 1 -
> > >> arch/arm/include/asm/highmem.h | 56 ++---------------------------
> > >> arch/arm/mm/cache-feroceon-l2.c | 31 ++--------------
> > >> arch/arm/mm/cache-xsc3l2.c | 47 +++---------------------
> > >> arch/arm/mm/dma-mapping.c | 12 ++-----
> > >> arch/arm/mm/flush.c | 19 +++-------
> > >> 9 files changed, 16 insertions(+), 153 deletions(-)
> > >
> > > This looks great, but do you think there should be a boot time crash
> > > if a VIVT and HIGHMEM are enabled, just incase?
> >
> > Do you mean in the common code or just for Arm?
> >
> > We could use the Arm specific cache_is_vivt() macro, but it feels like
> > the 'dpends on !CPU_CACHE_VIVT' Kconfig check I added is both
> > safer and simpler.
>
> Okay, so maybe I'm asking if !CPU_CACHE_VIVT then the kernel fails to
> boot on vivt systems, maybe it already does?
The cache modes (CPU_CACHE_xxx) are (were) selected by the processor
config entries. Not having the correct processor support built in to
the kernel will cause a boot failure.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2026-01-02 12:30 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-19 16:15 [PATCH 0/4] mm: increase lowmem size in linux-7.0 Arnd Bergmann
2025-12-19 16:15 ` [PATCH 1/4] arch/*: increase lowmem size to avoid highmem use Arnd Bergmann
2025-12-19 18:02 ` Dave Hansen
2025-12-19 20:20 ` Arnd Bergmann
2025-12-19 20:52 ` Dave Hansen
2025-12-20 12:17 ` Arnd Bergmann
2026-01-06 17:01 ` Dave Hansen
2025-12-21 9:30 ` David Hildenbrand (Red Hat)
2025-12-21 15:26 ` H. Peter Anvin
2025-12-24 11:35 ` Christophe Leroy (CS GROUP)
2026-01-08 14:32 ` Christophe Leroy (CS GROUP)
2025-12-19 16:15 ` [PATCH 2/4] ARM: add CONFIG_VMSPLIT_2G_OPT option Arnd Bergmann
2025-12-19 16:15 ` [PATCH 3/4] ARM: remove support for highmem on VIVT Arnd Bergmann
2025-12-19 17:14 ` Jason Gunthorpe
2025-12-19 20:34 ` Arnd Bergmann
2025-12-24 2:26 ` Jason Gunthorpe
2025-12-24 10:39 ` Arnd Bergmann
2026-01-02 12:12 ` Russell King (Oracle) [this message]
2025-12-19 16:15 ` [PATCH 4/4] mm: remove ARCH_NEEDS_KMAP_HIGH_GET Arnd Bergmann
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