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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-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-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4A1DF16000A 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=unavailable autolearn_force=no version=4.0.1 X-Stat-Signature: 53j75wouczyux8i3qkthzqa7k5pnc4ue X-Rspam-User: X-HE-Tag: 1794597626-913895 X-HE-Meta: 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 g4QSpc2B z0acBJloo1MEPpDkYIHgmahd2YRyjUUQMqRpLSiWIKewtqdanf0hf5lS1BK9MsaGvgYcD4FzVwXDjGOioQI+lMcLdCDBKv8mdHUXlrNHKwMjXiv49AGa+w4eS+nwkvzx93UUb9JIQ5Kt9HKD0u7U+22iiogiKJvth8tn4AdXIWBxSZGiAzZ8Z6xv+w3V4oViQSnN6K03IcE9kVDN8SYUnh3BMl3ewzPKIP1OxTsdr2RKqCJzpaowzjFu/C727HfJJgRG1fRCw4Q9tEKOhw33SikFAc8ayuVG2n0PI1ciZvHw9JM3lNHilLXV4xSrKqQhk3Vty Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: 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