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In preparation for reducing the phys-to-virt minimum relative alignment from 16 MiB to 2 MiB, switch to patchable sequences involving MOVW instructions that can more easily be manipulated to carry a 12-bit immediate. Note that the non-LPAE ARM sequence is not updated: MOVW may not be supported on non-LPAE platforms, and the sequence itself can be updated more easily to apply the 12 bits of displacement. For Thumb2, which has many more versions of opcodes, switch to a sequence that can be patched by the same patching code for both versions. Note that the Thumb2 opcodes for MOVW and MVN are unambiguous, and have no rotation bits in their immediate fields, so there is no need to use placeholder constants in the asm blocks. While at it, drop the 'volatile' qualifiers from the asm blocks: the code does not have any side effects that are invisible to the compiler, so it is free to omit these sequences if the outputs are not used. Suggested-by: Russell King <linux@armlinux.org.uk> Acked-by: Nicolas Pitre <nico@fluxnic.net> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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.