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@socionext.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190705100144.28785-1-yamada.masahiro@socionext.com
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