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Commit1d2e9b67b0("ARM: 9265/1: pass -march= only to compiler") added a __thumb2__ define to ASFLAGS to avoid build errors in the crypto code, which relies on __thumb2__ for preprocessing. Commit59e2cf8d21("ARM: 9275/1: Drop '-mthumb' from AFLAGS_ISA") followed up on this by removing -mthumb from AFLAGS so that __thumb2__ would not be defined when the default target was ARMv7 or newer. Unfortunately, the second commit's fix assumes that the toolchain defaults to -mno-thumb / -marm, which is not the case for Debian's arm-linux-gnueabihf target, which defaults to -mthumb: $ echo | arm-linux-gnueabihf-gcc -dM -E - | grep __thumb #define __thumb2__ 1 #define __thumb__ 1 This target is used by several CI systems, which will still see redefined macro warnings, despite '-mthumb' not being present in the flags: <command-line>: warning: "__thumb2__" redefined <built-in>: note: this is the location of the previous definition Remove the global AFLAGS __thumb2__ define and move it to the crypto folder where it is required by the imported OpenSSL algorithms; the rest of the kernel should use the internal CONFIG_THUMB2_KERNEL symbol to know whether or not Thumb2 is being used or not. Be sure that __thumb2__ is undefined first so that there are no macro redefinition warnings. Link: https://github.com/ClangBuiltLinux/linux/issues/1772 Reported-by: "kernelci.org bot" <bot@kernelci.org> Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Fixes:59e2cf8d21("ARM: 9275/1: Drop '-mthumb' from AFLAGS_ISA") Fixes:1d2e9b67b0("ARM: 9265/1: pass -march= only to compiler") Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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.