Re: [PATCH v3 1/2] powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h

[Michael Ellerman]

On Fri, 2019-07-05 at 10:01:43 UTC, Masahiro Yamada wrote:
> The next commit will make the way of passing CONFIG options more robust.
> Unfortunately, it would uncover another hidden issue; without this
> commit, skiroot_defconfig would be broken like this:
> 
> |   WRAP    arch/powerpc/boot/zImage.pseries
> | arch/powerpc/boot/wrapper.a(decompress.o): In function `bcj_powerpc.isra.10':
> | decompress.c:(.text+0x720): undefined reference to `get_unaligned_be32'
> | decompress.c:(.text+0x7a8): undefined reference to `put_unaligned_be32'
> | make[1]: *** [arch/powerpc/boot/Makefile;383: arch/powerpc/boot/zImage.pseries] Error 1
> | make: *** [arch/powerpc/Makefile;295: zImage] Error 2
> 
> skiroot_defconfig is the only defconfig that enables CONFIG_KERNEL_XZ
> for ppc, which has never been correctly built before.
> 
> I figured out the root cause in lib/decompress_unxz.c:
> 
> | #ifdef CONFIG_PPC
> | #      define XZ_DEC_POWERPC
> | #endif
> 
> CONFIG_PPC is undefined here in the ppc bootwrapper because autoconf.h
> is not included except by arch/powerpc/boot/serial.c
> 
> XZ_DEC_POWERPC is not defined, therefore, bcj_powerpc() is not compiled
> for the bootwrapper.
> 
> With the next commit passing CONFIG_PPC correctly, we would realize that
> {get,put}_unaligned_be32 was missing.
> 
> Unlike the other decompressors, the ppc bootwrapper duplicates all the
> necessary helpers in arch/powerpc/boot/.
> 
> The other architectures define __KERNEL__ and pull in helpers for
> building the decompressors.
> 
> If ppc bootwrapper had defined __KERNEL__, lib/xz/xz_private.h would
> have included <asm/unaligned.h>:
> 
> | #ifdef __KERNEL__
> | #       include <linux/xz.h>
> | #       include <linux/kernel.h>
> | #       include <asm/unaligned.h>
> 
> However, doing so would cause tons of definition conflicts since the
> bootwrapper has duplicated everything.
> 
> I just added copies of {get,put}_unaligned_be32, following the
> bootwrapper coding convention.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/9e005b761e7ad153dcf40a6cba1d681fe0830ac6

cheers