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commit0648e50e54upstream. The MIPS VDSO build currently doesn't provide the -msoft-float flag to the compiler as the kernel proper does. This results in an attempt to use the compiler's default floating point configuration, which can be problematic in cases where this is incompatible with the target CPU's -march= flag. For example decstation_defconfig fails to build using toolchains in which gcc was configured --with-fp-32=xx with the following error: LDS arch/mips/vdso/vdso.lds cc1: error: '-march=r3000' requires '-mfp32' make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1 The kernel proper avoids this error because we build with the -msoft-float compiler flag, rather than using the compiler's default. Pass this flag through to the VDSO build so that it too becomes agnostic to the toolchain's floating point configuration. Note that this is filtered out from KBUILD_CFLAGS rather than simply always using -msoft-float such that if we switch the kernel to use -mno-float in the future the VDSO will automatically inherit the change. The VDSO doesn't actually include any floating point code, and its .MIPS.abiflags section is already manually generated to specify that it's compatible with any floating point ABI. As such this change should have no effect on the resulting VDSO, apart from fixing the build failure for affected toolchains. Signed-off-by: Paul Burton <paul.burton@mips.com> Reported-by: Kevin Hilman <khilman@baylibre.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Kevin Hilman <khilman@baylibre.com> References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/ References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ Fixes:ebb5e78cc6("MIPS: Initial implementation of a VDSO") Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.4+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.