Hi Tom,
trini@konsulko.com wrote on Wed, 1 Jun 2022 10:08:20 -0400:
On Thu, Apr 07, 2022 at 11:58:55AM +0200, Pali Rohár wrote:
On Thursday 07 April 2022 11:54:55 Miquel Raynal wrote:
Hi Pali,
pali@kernel.org wrote on Thu, 7 Apr 2022 11:41:59 +0200:
On Thursday 07 April 2022 09:54:21 Miquel Raynal wrote:
Hi Pali,
pali@kernel.org wrote on Wed, 6 Apr 2022 23:31:53 +0200:
Would you mind explaining a little bit how this change fixes it? It does not look straightforward to me.
Yes! I though that it is straightforward this change... byteorder/little_endian.h defines cpu_to_le* macros for Little Endian systems and byteorder/big_endian.h for Big Endian systems.
File asm/byteorder.h is then ARCH-specific and implements macros for the current architecture (by including the correct header file).
So currently if you try to compile squashfs for big endian systems you get compile error:
In file included from ./arch/powerpc/include/asm/byteorder.h:82, from include/linux/unaligned/access_ok.h:4, from ./arch/powerpc/include/asm/unaligned.h:9, from fs/squashfs/sqfs_filesystem.h:11, from fs/squashfs/sqfs_dir.c:16: include/linux/byteorder/big_endian.h:34: warning: "__cpu_to_le32" redefined #define __cpu_to_le32(x) ((__force __le32)__swab32((x)))
In file included from fs/squashfs/sqfs_dir.c:10: include/linux/byteorder/little_endian.h:34: note: this is the location of the previous definition #define __cpu_to_le32(x) ((__force __le32)(__u32)(x))
Or:
In file included from fs/squashfs/sqfs.c:14: include/linux/byteorder/little_endian.h:89:21: error: redefinition of ‘__be16_to_cpup’ static inline __u16 __be16_to_cpup(const __be16 *p) ^~~~~~~~~~~~~~ In file included from ./arch/powerpc/include/asm/byteorder.h:82, from include/linux/unaligned/access_ok.h:4, from ./arch/powerpc/include/asm/unaligned.h:9, from fs/squashfs/sqfs.c:10: include/linux/byteorder/big_endian.h:89:21: note: previous definition of ‘__be16_to_cpup’ was here static inline __u16 __be16_to_cpup(const __be16 *p) ^~~~~~~~~~~~~~
As some header files include correct asm/byteorder.h file and this squashfs includes additional little_endian.h.
Great, thanks for the thorough explanation. Based on what you said, wouldn't it be cleaner to just get rid of the little_endian.h include rather than also use the ARCH specific byteorder.h header?
I think that this is not possible. squashfs code uses le16_to_cpu() macro and its correct definition is provided only by arch specific asm/byteorder.h.
Miquel, is this sufficient explanation? Thanks.
Yes, sorry, it seems like in U-Boot including the asm header is the way to go, so:
Reviewed-by: Miquel Raynal miquel.raynal@bootlin.com
Thanks, Miquèl