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Fri, 13 Nov 2026 19:20:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794597624; bh=Yme8xVrfiJB9JtUWZsCWQb4f6bpQ8C2lB7x46RDJgew=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=W6dxepisHpNNsxivi81mY2JUyom8vDvbtSJGZ79fX/VnHuW46WgDlfEp5w7M4L57I LCYDzH5U0zSkM86UX6S5jGE9QpxapZ2vXxyGRwBFCxzwa1hnqIs2B5C1sd9o1Obgcp MFZVnbFcDAFxRX01z+kkFJPV818yQD1kIbDRb8w1KLadEiSWsjM6L69B0/DeYUaKKJ JnHV9Zjv20wthE9X+dPxf1pxS/GCxyevGUDxAU7fMzVkPg2hHRB2S01RE3gZ9BRIKm zBYjPZQY9VUggt4Lrn/MTj4XrA5pKIELlXIqABDX1noeaFuneVjKllspDykcclkRE9 OuumQ6HJ3hVhQ== Date: Fri, 13 Nov 2026 19:20:17 +0000 From: "Lorenzo Stoakes (ARM)" To: Arnd Bergmann Cc: linux-mm@kvack.org, Arnd Bergmann , Andrew Morton , Andreas Larsson , "Christophe Leroy (CS GROUP)" , Dave Hansen , "David Hildenbrand (Arm)" , Jason Gunthorpe , Linus Walleij , Matthew Wilcox , Malin Jonsson , Richard Weinberger , Russell King , linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: Re: [PATCH v2 6/6] ARM: add CONFIG_VMSPLIT_2G_OPT option Message-ID: References: <20261112112528.1116405-1-arnd@kernel.org> <20261112112528.1116405-7-arnd@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261112112528.1116405-7-arnd@kernel.org> X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 12, 2026 at 12:25:28PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > Unlike x86 and powerpc, there is currently no option to use exactly 2GiB > of lowmem on Arm. Since 2GiB is still a relatively common configuration > on embedded systems, it makes sense to allow this to be used in > non-highmem builds. > > Add the Kconfig option and make this the default for non-LPAE builds > with highmem enabled instead of CONFIG_VMSPLIT_2G. LPAE still requires > the vmsplit to be on a gigabyte boundary, so this is only available for > classic pagetables at the moment, same as CONFIG_VMSPLIT_3G_OPT. > > Tested in qemu -M virt, both with and without HIGHMEM enabled. > > Signed-off-by: Arnd Bergmann With sashiko fix, LGTM and: Acked-by: Lorenzo Stoakes (ARM) > --- > arch/arm/Kconfig | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 797705a94b28..8992fedfdf37 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1025,7 +1025,8 @@ config BL_SWITCHER_DUMMY_IF > choice > prompt "Memory split" > depends on MMU > - default VMSPLIT_2G if HIGHMEM || ARM_LPAE > + default VMSPLIT_2G if ARM_LPAE > + default VMSPLIT_2G_OPT if HIGHMEM > default VMSPLIT_3G_OPT > help > Select the desired split between kernel and user memory. > @@ -1042,6 +1043,9 @@ choice > bool "3G/1G user/kernel split (for full 1G low memory)" > config VMSPLIT_2G > bool "2G/2G user/kernel split" > + config VMSPLIT_2G_OPT > + depends on !ARM_LPAE > + bool "2G/2G user/kernel split (for full 2G low memory)" > config VMSPLIT_1G > bool "1G/3G user/kernel split" > endchoice > @@ -1050,6 +1054,7 @@ config PAGE_OFFSET > hex > default PHYS_OFFSET if !MMU > default 0x40000000 if VMSPLIT_1G > + default 0x70000000 if VMSPLIT_2G_OPT > default 0x80000000 if VMSPLIT_2G > default 0xB0000000 if VMSPLIT_3G_OPT > default 0xC0000000 > @@ -1058,6 +1063,7 @@ config KASAN_SHADOW_OFFSET > hex > depends on KASAN > default 0x1f000000 if PAGE_OFFSET=0x40000000 > + default 0x4f000000 if PAGE_OFFSET=0x70000000 > default 0x5f000000 if PAGE_OFFSET=0x80000000 > default 0x9f000000 if PAGE_OFFSET=0xC0000000 > default 0x8f000000 if PAGE_OFFSET=0xB0000000 > -- > 2.53.0 > -- Cheers, Lorenzo