ce7904b88e
linux-user: default to -cpu max (rhbz#2121700) Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
82 lines
3.0 KiB
Diff
82 lines
3.0 KiB
Diff
From ea3de64a58f5f157a75280bcddf884c5bda391be Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>
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Date: Fri, 23 Sep 2022 12:04:13 +0100
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Subject: [PATCH 21/21] linux-user: use 'max' instead of 'qemu32' / 'qemu64' by
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default
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The 'qemu64' CPU model implements the least featureful x86_64 CPU that's
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possible. Historically this hasn't been an issue since it was rare for
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OS distros to build with a higher mandatory CPU baseline.
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With RHEL-9, however, the entire distro is built for the x86_64-v2 ABI
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baseline:
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https://developers.redhat.com/blog/2021/01/05/building-red-hat-enterprise-linux-9-for-the-x86-64-v2-microarchitecture-level
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It is likely that other distros may take similar steps in the not too
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distant future. For example, it has been suggested for Fedora on a
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number of occasions.
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This new baseline is not compatible with the qemu64 CPU model though.
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While it is possible to pass a '-cpu xxx' flag to qemu-x86_64, the
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usage of QEMU doesn't always allow for this. For example, the args
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are typically controlled via binfmt rules that the user has no ability
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to change. This impacts users who are trying to use podman on aarch64
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platforms, to run containers with x86_64 content. There's no arg to
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podman that can be used to change the qemu-x86_64 args, and a non-root
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user of podman can not change binfmt rules without elevating privileges:
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https://github.com/containers/podman/issues/15456#issuecomment-1228210973
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Changing to the 'max' CPU model gives 'qemu-x86_64' maximum
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compatibility with binaries it is likely to encounter in the wild,
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and not likely to have a significant downside for existing usage.
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Most other architectures already use an 'any' CPU model, which is
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often mapped to 'max' (or similar) already, rather than the oldest
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possible CPU model.
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For the sake of consistency the 'i386' architecture is also changed
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from using 'qemu32' to 'max'.
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Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
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Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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Message-Id: <20220923110413.70593-1-berrange@redhat.com>
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Signed-off-by: Laurent Vivier <laurent@vivier.eu>
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---
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linux-user/i386/target_elf.h | 2 +-
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linux-user/x86_64/target_elf.h | 2 +-
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2 files changed, 2 insertions(+), 2 deletions(-)
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diff --git a/linux-user/i386/target_elf.h b/linux-user/i386/target_elf.h
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index 1c6142e..238a9ab 100644
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--- a/linux-user/i386/target_elf.h
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+++ b/linux-user/i386/target_elf.h
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@@ -9,6 +9,6 @@
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#define I386_TARGET_ELF_H
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static inline const char *cpu_get_model(uint32_t eflags)
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{
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- return "qemu32";
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+ return "max";
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}
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#endif
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diff --git a/linux-user/x86_64/target_elf.h b/linux-user/x86_64/target_elf.h
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index 7b76a90..3f628f8 100644
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--- a/linux-user/x86_64/target_elf.h
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+++ b/linux-user/x86_64/target_elf.h
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@@ -9,6 +9,6 @@
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#define X86_64_TARGET_ELF_H
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static inline const char *cpu_get_model(uint32_t eflags)
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{
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- return "qemu64";
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+ return "max";
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}
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#endif
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--
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2.39.0
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