• Arnd Bergmann's avatar
    ARM: 7743/1: compressed/head.S: work around new binutils warning · da94a829
    Arnd Bergmann authored
    In August 2012, Matthew Gretton-Dann checked a change into binutils
    labelled "Error on obsolete & warn on deprecated registers", apparently as
    part of ARMv8 support. Apparently, this was supposed to emit the message
    "Warning: This coprocessor register access is deprecated in ARMv8" when
    using certain mcr/mrc instructions and building for ARMv8. Unfortunately,
    the message that is actually emitted appears to be '(null)', which is
    less helpful in comparison.
    
    Even more unfortunately, this is biting us on every single kernel
    build with a new gas, because arch/arm/boot/compressed/head.S and some
    other files in that directory are built with -march=all since kernel
    commit 80cec14a "[ARM] Add -march=all to assembly file build in
    arch/arm/boot/compressed" back in v2.6.28.
    
    This patch reverts Russell's nice solution and instead marks the head.S
    file to be built for armv7-a, which fortunately lets us build all
    instructions in that file without warnings even on the broken binutils.
    
    Without this patch, building anything results in:
    
    arch/arm/boot/compressed/head.S: Assembler messages:
    arch/arm/boot/compressed/head.S:565: Warning: (null)
    arch/arm/boot/compressed/head.S:676: Warning: (null)
    arch/arm/boot/compressed/head.S:698: Warning: (null)
    arch/arm/boot/compressed/head.S:722: Warning: (null)
    arch/arm/boot/compressed/head.S:726: Warning: (null)
    arch/arm/boot/compressed/head.S:957: Warning: (null)
    arch/arm/boot/compressed/head.S:996: Warning: (null)
    arch/arm/boot/compressed/head.S:997: Warning: (null)
    arch/arm/boot/compressed/head.S:1027: Warning: (null)
    arch/arm/boot/compressed/head.S:1035: Warning: (null)
    arch/arm/boot/compressed/head.S:1046: Warning: (null)
    arch/arm/boot/compressed/head.S:1060: Warning: (null)
    arch/arm/boot/compressed/head.S:1092: Warning: (null)
    arch/arm/boot/compressed/head.S:1094: Warning: (null)
    arch/arm/boot/compressed/head.S:1095: Warning: (null)
    arch/arm/boot/compressed/head.S:1102: Warning: (null)
    arch/arm/boot/compressed/head.S:1134: Warning: (null)
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Cc: stable@vger.kernel.org
    Cc: Matthew Gretton-Dann <matthew.gretton-dann@arm.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    da94a829
head.S 31.1 KB