linux-kernel - Re: [PATCH 15/15] x86/kconfig/32: Synchronize the x86-32 defconfig to the x86-64 defconfig

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <667849c3-e522-4fbb-9d45-fbe28f7e6da7@app.fastmail.com>
Date: Wed, 07 May 2025 07:27:53 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Ingo Molnar" <mingo@...nel.org>, linux-kernel@...r.kernel.org
Cc: "H. Peter Anvin" <hpa@...or.com>,
 "Linus Torvalds" <torvalds@...ux-foundation.org>,
 "Peter Zijlstra" <peterz@...radead.org>, "Borislav Petkov" <bp@...en8.de>,
 "Thomas Gleixner" <tglx@...utronix.de>,
 "Vitaly Kuznetsov" <vkuznets@...hat.com>, "Ard Biesheuvel" <ardb@...nel.org>,
 "David Woodhouse" <dwmw@...zon.co.uk>,
 "Masahiro Yamada" <yamada.masahiro@...ionext.com>,
 "Michal Marek" <michal.lkml@...kovi.net>
Subject: Re: [PATCH 15/15] x86/kconfig/32: Synchronize the x86-32 defconfig to the
 x86-64 defconfig

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.

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?

> @@ -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.

> @@ -234,6 +295,8 @@ CONFIG_DMADEVICES=y
>  CONFIG_VIRTIO_PCI=y
>  CONFIG_VIRTIO_INPUT=y
>  CONFIG_EEEPC_LAPTOP=y
> +CONFIG_INTEL_IOMMU=y
> +# CONFIG_INTEL_IOMMU_DEFAULT_ON is not set

I'm pretty sure the Intel IOMMU was only in 64-bit chips.

    Arnd