From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3FDD728C853 for ; Wed, 7 May 2025 17:41:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746639672; cv=none; b=oA4wNw3Hmz5Yrjj3QbGKes8cIN0zX+UjQF31b0Im2qGGGDfrQwMSuM9DgLmPk7g58ObsQTF7FeUR+NK9PsM6FcO9hNAsDqLSGrjgCewGF1UTpNvsnpj94BFabKEPHuR8358MEYlvOBnKut/0ehwo3CBmG7wbni5zDxGS4NL4JYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746639672; c=relaxed/simple; bh=FL4IeKrUspWVyp1tk9VzMiFnHwB23qw+vDWGRZbzPBM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pyB0ykRVLhDQgHN5YejjjCYkUIbN49YpKI//o7Y+40JoQ7A0GdwCBqoWPU8dLgVtOxgc7m+4ZYX5oqFXUFMNDAMxIt8xh8Rx1WRgXtSNmxQt9oFa/+FZzbKVrDbtCdicg6vWY0+JtVZCqVO+1RK+63iuHfYpXw/TmHxElE8qi/s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nbLWgj3J; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nbLWgj3J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0406C4CEE2; Wed, 7 May 2025 17:41:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746639671; bh=FL4IeKrUspWVyp1tk9VzMiFnHwB23qw+vDWGRZbzPBM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nbLWgj3JmJ31+V389MiRWKysVLZyLMm7eino0x21Azs3KyacL+DinO+8yMWn9aeeO MQtxi6n8FM2JKYpVg7lkOp6kau+f4arYE0yRzGM3WJNP4D5HVdfLoD4RS8AVA3totO sDwXIermbDpd1IF6Md56Epqbl4ON+7bm7SxFk5/8SZuE+1vzyZskSUwZ2Gua1vgPJR /UXTsENqXABiN9/zEO0Yl/78uXQGXMKcfc2xqq+xb+LQf/9XA9NZwtVM3aEYs2GiSk C9s3kY+F+8knTBgDWFSAtQMz05X4l3DHs8Pzul0iEeh0qVWCVhSvMrC9JGuy4bh3Sv Ml598W/FhihlQ== Date: Wed, 7 May 2025 19:41:06 +0200 From: Ingo Molnar To: Arnd Bergmann Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" , Linus Torvalds , Peter Zijlstra , Borislav Petkov , Thomas Gleixner , Vitaly Kuznetsov , Ard Biesheuvel , David Woodhouse , Masahiro Yamada , Michal Marek Subject: Re: [PATCH 15/15] x86/kconfig/32: Synchronize the x86-32 defconfig to the x86-64 defconfig Message-ID: References: <20250506170924.3513161-1-mingo@kernel.org> <20250506170924.3513161-16-mingo@kernel.org> <667849c3-e522-4fbb-9d45-fbe28f7e6da7@app.fastmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <667849c3-e522-4fbb-9d45-fbe28f7e6da7@app.fastmail.com> * Arnd Bergmann wrote: > On Tue, May 6, 2025, at 19:09, Ingo Molnar wrote: > > > Just a mechanic synchronization of kernel options enabled: nobody > > really develops kernel features on x86-32 anymore, so make sure the > > defconfig is roughly equivalent to the 64-bit one, so that testing > > doesn't cover some combination that nobody cares about. > > What is the size increase here? > > Some of the options you enable look like they might add a lot of code > to the vmlinux binary, and 32-bit are often might more limited than > 64-bit ones. 16.5MB -> 20.8MB, so well within usual RAM limits of x86-32 testing. As a comparison, the last x86-32 Debian version's kernel, based on v6.1, has a vmlinux with 12.2MB .text and 4.2MB of modules loaded when booted into text mode, so 16.4MB total. This goes up substantially if any graphics is loaded. > IOW, is your goal here to keep something that works on actual 32-bit > machines, or do you want something that will in practice run on > 64-bit machines and have a comparable feature set? This will work on the vast majority of actual 32-bit machines in the i686 class and above, but the primary users are kernel developers doing test-runs on x86-64. For those who have less than 1GB of RAM, there's always tiny-base.config. > > @@ -50,7 +76,11 @@ CONFIG_ACPI_BGRT=y > > CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y > > CONFIG_CPU_FREQ_GOV_ONDEMAND=y > > CONFIG_X86_ACPI_CPUFREQ=y > > -CONFIG_KPROBES=y > > +CONFIG_KVM=y > > +CONFIG_KVM_INTEL=y > > +CONFIG_KVM_AMD=y > > +CONFIG_KVM_XEN=y > > +CONFIG_KVM_MAX_NR_VCPUS=4096 > > CONFIG_JUMP_LABEL=y > > CONFIG_COMPAT_32BIT_TIME=y > > CONFIG_MODULES=y > > I have a series to completely remove KVM support for 32-bit. There is > one powerpc platform that may keep it, but there is really no point > in enabling it here when there are practically zero 32-bit machines > that can use it. That's OK, it will go away once it's removed. This is an intentionally mechanical mirroring of the 64-bit Kconfig over to 32-bit, we've done this in the past as well. Thanks, Ingo