From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7320E3148D3; Wed, 1 Jul 2026 21:24:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782941081; cv=none; b=S6TjimEBQEudNBfVAqby+Shsi90mSLa6+Xy48hYXGeaFeC1ymjtkW//oqz65sQCAL3738j0jRD0XSufwvX5VuwRfYRiBZwneDPgtSgf2/epovUhjEJw6n2cLhcC//PRfQ3gZPr85Z7w/Wep3szdMdKWvW7T9KH9YxN95QaChKd8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782941081; c=relaxed/simple; bh=PSH/tEAjQFqBlr1rGEhXiBaOEXYzZfQOuhbAbK4Kzq4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WVMNx330pLxesfYrwCXjXercKRfNrbZT9vDzPQY/KYpKL/eG1kpDPmgbIbJp5Tv5UT9NVzuNMoaxIcNXFx/iuDCNQAYqYTc3ZQsFQyVAgcAMXwWH9LeEQas3WK5fya0XVHTGS1O29I7NCfGRrMplfSZk0MKwtPy1+3vbNCbAJG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KR49V9z6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KR49V9z6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71DA81F00A3A; Wed, 1 Jul 2026 21:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782941077; bh=pW3IZOu0mVg5k08ZXT4Rxcybnx6gB+8NKIZoUCTYQ3w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KR49V9z6Q23APTk3k9NJ80lOE+2nglsiTE3DKpr56zQEjoqCPalvhy715ZIw1pUSD nJecdPUoc8dwlSirpO8g/FE+g+L34ai8YYRp9DL583xNODwoKvmzT0kZc0t/HCXOri J7+SNt1iDjM1VQDn0NwTarnApV48Wej5gRqdMGE6BDWDliUCaK9RJ1wxWxB1zE50kE C7fwmFzREe08D3glXfWuDMG4PBvAzCfwawVcm7/Vrt98uxyfr0qHeXjEgfx+5vrlUz przaJxeoisNduqnBVbntXl+JX5iqofvybWsTBZ6jygBHQwC440Pxu3KS5k/CP1t/Yc FnEah/BftKnLQ== From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org, soc@lists.linux.dev Cc: linux-kernel@vger.kernel.org, Arnd Bergmann , Aaro Koskinen , Alexander Sverdlin , Alexandre Belloni , Alexandre Torgue , Andrew Lunn , Ard Biesheuvel , Claudiu Beznea , Daniel Mack , Ethan Nelson-Moore , Frank Li , Gregory Clement , Haojian Zhuang , "Jeremy J. Peper" , Kristoffer Ericson , Krzysztof Kozlowski , Linus Walleij , Mark Brown , Marc Zyngier , Mike Rapoport , Nicolas Ferre , Patrice Chotard , Ralph Siemsen , Robert Jarzmik , Russell King , Sascha Hauer , Sebastian Hesselbarth , Stefan Agner , Stefan Wiehler , Tony Lindgren , Vladimir Zapolskiy , Will Deacon , Linus Walleij Subject: [PATCH v2 03/19] ARM: rework ARM11 CPU selection logic Date: Wed, 1 Jul 2026 23:23:37 +0200 Message-Id: <20260701212353.2196041-4-arnd@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260701212353.2196041-1-arnd@kernel.org> References: <20260701212353.2196041-1-arnd@kernel.org> Precedence: bulk X-Mailing-List: soc@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Arnd Bergmann Support for SMP on ARM1136r0 has been broken for a while, and nobody is working on fixing it. I had a plan to change ARMv6 support to no longer coexist in a common kernel with ARMv7 CPUs but instead ARMv5 and below. This would have addressed the problem, but after a recent mailing list discussion, we concluded that an easier approach is to just forbid ARM1136r0 CPU support on SMP-enabled kernels. This mainly affects users of the Nokia N800/N810 tablets using an OMAP2420 SoC, which is the only commercial product with an ARM1136r0 that is still supported by the kernel. The other machines that are still in the same hardware catogory are: - TI OMAP2420 H4 reference board - TI OMAP2430 SDP software development platform - Freescale/NXP i.MX31 Lite Development Kit - Buglabs i.MX31 Bug 1.x prototype - Arm Integrator/AP with CM1136JF-S core module To my knowledge, none of these have any actual users aside from reference boards being used more easily test the platforms. There are also a few ARM1136r1 machines, which implement the ARMv6K SMP support (barriers, atomics and TLS): - Eukrea CPUIMX35 reference platform - Freescale/NXP i.MX35 Product Development Kit - ARM Integrator/CP/IM-LT3 with ARM1136J Core Tile - ARM Realview/EB with ARM1136J Core Tile Again, these are mainly reference implementations rather than actual products, but since they support ARMv6K, they should continue to work correctly in SMP-enabled kernels. For the ARM Core Tile, I have not found a datasheet but instead use the revision based on what the respective virtual models report. All the other ARMv6 platforms use an ARM1176 with ARMv6K, VMSAv7 and Trustzone support. To avoid the broken configuration, annotate the ARM1136 based machines with specific CPU_ARM1136R0 or CPU_ARM1136R2 symbols in Kconfig and make the r0 variants depend on !SMP. Link: https://lore.kernel.org/linux-arm-kernel/2831c5a6-cfbf-4fe0-b51c-0396e5b0aeb7@app.fastmail.com/T/ Acked-by: Linus Walleij Signed-off-by: Arnd Bergmann --- arch/arm/Kconfig.platforms | 2 +- arch/arm/mach-imx/Kconfig | 4 +++- arch/arm/mach-omap2/Kconfig | 3 ++- arch/arm/mach-versatile/Kconfig | 10 +++++----- arch/arm/mm/Kconfig | 24 +++++++++++++++++++++++- 5 files changed, 34 insertions(+), 9 deletions(-) diff --git a/arch/arm/Kconfig.platforms b/arch/arm/Kconfig.platforms index 386eccc81868..2e118b65f93b 100644 --- a/arch/arm/Kconfig.platforms +++ b/arch/arm/Kconfig.platforms @@ -33,7 +33,7 @@ config ARCH_MULTI_V4_V5 config ARCH_MULTI_V6 bool "ARMv6 based platforms (ARM11)" select ARCH_MULTI_V6_V7 - select CPU_V6K + select CPU_ARM1176 config ARCH_MULTI_V7 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)" diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig index a361840d7a04..041e73ad203a 100644 --- a/arch/arm/mach-imx/Kconfig +++ b/arch/arm/mach-imx/Kconfig @@ -41,13 +41,15 @@ comment "ARM1136 platforms" config SOC_IMX31 bool "i.MX31 support" - select CPU_V6 + depends on !SMP + select CPU_ARM1136R0 select MXC_AVIC help This enables support for Freescale i.MX31 processor config SOC_IMX35 bool "i.MX35 support" + select CPU_ARM1136R1 select MXC_AVIC help This enables support for Freescale i.MX35 processor diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig index f3f19bcfca2c..13987ffbba00 100644 --- a/arch/arm/mach-omap2/Kconfig +++ b/arch/arm/mach-omap2/Kconfig @@ -8,8 +8,9 @@ config OMAP_HWMOD config ARCH_OMAP2 bool "TI OMAP2" depends on ARCH_MULTI_V6 + depends on !SMP select ARCH_OMAP2PLUS - select CPU_V6 + select CPU_ARM1136R0 select OMAP_HWMOD select SOC_HAS_OMAP2_SDRC diff --git a/arch/arm/mach-versatile/Kconfig b/arch/arm/mach-versatile/Kconfig index 513618078440..de42da7de8c8 100644 --- a/arch/arm/mach-versatile/Kconfig +++ b/arch/arm/mach-versatile/Kconfig @@ -113,7 +113,8 @@ config INTEGRATOR_CM1136JFS bool "Integrator/CM1136JF-S core module" depends on ARCH_INTEGRATOR_AP depends on ARCH_MULTI_V6 - select CPU_V6 + depends on !SMP + select CPU_ARM1136R0 config ARCH_INTEGRATOR_CP bool "Support Integrator/CP platform" @@ -135,7 +136,7 @@ config INTEGRATOR_CTB36 bool "Integrator/CTB36 (ARM1136JF-S) core tile" depends on ARCH_INTEGRATOR_CP depends on ARCH_MULTI_V6 - select CPU_V6 + select CPU_ARM1136R1 config ARCH_CINTEGRATOR depends on ARCH_INTEGRATOR_CP @@ -182,7 +183,7 @@ config MACH_REALVIEW_EB config REALVIEW_EB_ARM1136 bool "Support ARM1136J(F)-S Tile" depends on MACH_REALVIEW_EB && ARCH_MULTI_V6 - select CPU_V6 + select CPU_ARM1136R1 help Enable support for the ARM1136 tile fitted to the Realview(R) Emulation Baseboard platform. @@ -201,11 +202,10 @@ config REALVIEW_EB_A9MP Enable support for the Cortex-A9MPCore tile fitted to the Realview(R) Emulation Baseboard platform. -# ARMv6 CPU without K extensions, but does have the new exclusive ops config MACH_REALVIEW_PB1176 bool "Support RealView(R) Platform Baseboard for ARM1176JZF-S" depends on ARCH_MULTI_V6 - select CPU_V6 + select CPU_ARM1176 select HAVE_TCM help Include support for the ARM(R) RealView(R) Platform Baseboard for diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 871bd58d2ccc..f3d71e89a31f 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -376,6 +376,7 @@ config CPU_PJ4B # ARMv6 config CPU_V6 bool + depends on !SMP select CPU_32v6 select CPU_ABRT_EV6 select CPU_CACHE_V6 @@ -386,7 +387,6 @@ config CPU_V6 select CPU_PABRT_V6 select CPU_THUMB_CAPABLE select CPU_TLB_V6 if MMU - select SMP_ON_UP if SMP # ARMv6k config CPU_V6K @@ -403,6 +403,28 @@ config CPU_V6K select CPU_THUMB_CAPABLE select CPU_TLB_V6 if MMU +config CPU_ARM1136R0 + bool + select CPU_V6 + depends on !SMP + help + These early revisions of ARM1136 lack support for the + ARMv6k extensions for multiprocessing. + +config CPU_ARM1136R1 + bool + select CPU_V6K + help + Later revisions of ARM1136 add ARMv6k (atomics, barriers + and TLS register) in addition to the features from r0. + +config CPU_ARM1176 + bool + select CPU_V6K + help + ARM1176 implements ARMv6k, VMSAv7 and Trustzone in + addition to the ARMv6 baseline. + # ARMv7 and ARMv8 architectures config CPU_V7 bool -- 2.39.5