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Kernel uses ARCH=powerpc for both 32-bit and 64-bit PowerPC, here adds a ppc variant for 32-bit PowerPC and uses it as the default variant of powerpc architecture. Users can pass XARCH=ppc (or ARCH=powerpc) to test 32-bit PowerPC. The default qemu-system-ppc g3beige machine [1] is used to run 32-bit powerpc kernel with pmac32_defconfig. The missing PMACZILOG serial tty and console are enabled in another patch [2]. Note, - zImage doesn't boot due to "qemu-system-ppc: Some ROM regions are overlapping" error, so, vmlinux is used instead. - since the VSX support may be disabled in kernel side, to avoid "illegal instruction" errors due to missing VSX kernel support, let's simply let compiler not generate vector/scalar (VSX) instructions via the '-mno-vsx' option. - as 'man gcc' shows, '-mmultiple' is used to generate code that uses the load multiple word instructions and the store multiple word instructions. Those instructions do not work when the processor is in little-endian mode (except PPC740/PPC750), so, we only enable it for big endian powerpc. [1]: https://qemu.readthedocs.io/en/latest/system/ppc/powermac.html [2]: https://lore.kernel.org/lkml/bb7b5f9958b3e3a20f6573ff7ce7c5dc566e7e32.1690982937.git.tanyuan@tinylab.org/ Suggested-by: Willy Tarreau <w@1wt.eu> Link: https://lore.kernel.org/lkml/ZL9leVOI25S2+0+g@1wt.eu/ Reviewed-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Zhangjin Wu <falcon@tinylab.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.