• Jonathan Austin's avatar
    ARM: 7666/1: decompressor: add -mno-single-pic-base for building the decompressor · b8083f86
    Jonathan Austin authored
    Before jumping to (position independent) C-code from the decompressor's
    assembler world we set-up the C environment. This setup currently does not
    set r9, which for arm-none-uclinux-uclibceabi toolchains is by default
    expected to be the PIC offset base register (IE should point to the
    beginning of the GOT).
    
    Currently, therefore, in order to build working kernels that use the
    decompressor it is necessary to use an arm-linux-gnueabi toolchain, or
    similar. uClinux toolchains cause a prefetch abort to occur at the beginning
    of the decompress_kernel function.
    
    This patch allows uClinux toolchains to build bootable zImages by forcing
    the -mno-single-pic-base option, which ensures that the location of the GOT
    is re-derived each time it is required, and r9 becomes free for use as a
    general purpose register.
    
    This has a small (4% in instruction terms) advantage over the alternative of
    setting r9 to point to the GOT before calling into the C-world.
    Signed-off-by: default avatarJonathan Austin <jonathan.austin@arm.com>
    Acked-by: default avatarNicolas Pitre <nico@linaro.org>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    b8083f86
Makefile 5.43 KB