Re: reiserfs

[Jun Sun <jsun@mvista.com>]

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Pete Popov wrote:

> On Sat, 2002-04-27 at 13:19, Alan Cox wrote:
> 
>>>Has anyone been able to run reiserfs on big endian systems?
>>>
>>Should work on newer 2.4 kernels
>>
> 
> Yes, it does. I sent an email yesterday explaining what the problem
> was.  The 2.95.3 toolchain is miscompiling the cpu_to_le16 and
> le16_to_cpu functions. The problem appears to be fixed in 2.96 and 3.x
> so reiserfs is looking good for both, LE and BE mips systems.
> 


Here is the test case that reveals the toolchain problem.  Brave souls are 
welcome to look into it.

Apparently the bug only happens on be tools with 2.95.x.

Jun



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#if 0

compile instructions:

/opt/hardhat/devkit/mips/fp_be/bin/mips_fp_be-gcc -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -g -G 0 -mno-abicalls -fno-pic -mcpu=r4600 -mips2 -Wa,--trap -pipe    -c -o try.o try.c

#endif

typedef	unsigned short __u16;
typedef	unsigned __u32;

#define ___swab16_new(x) \
({ \
        __u32 __x = (x); \
        __x = ((__u32)( \
                ((__u32)(__x) << 8) | \
                (((__u32)(__x) & (__u16)0xff00U) >> 8) )); \
        (__u16)(__x & 0xffff); \
})

#define ___swab16(x) \
({ \
        __u16 __x = (x); \
        ((__u16)( \
                (((__u16)(__x) & (__u16)0x00ffU) << 8) | \
                (((__u16)(__x) & (__u16)0xff00U) >> 8) )); \
})

#  define __swab16(x) \
(__builtin_constant_p((__u16)(x)) ? \
  ___swab16((x)) : \
   __fswab16((x)))

#ifndef __arch__swab16
#  define __arch__swab16(x) ({ __u16 __tmp = (x) ; ___swab16(__tmp); })
#endif

static __inline__ __const__ __u16 __fswab16(__u16 x)
{
	        return __arch__swab16(x);
}

#define __le16_to_cpu(x) __swab16((x))
#define le16_to_cpu __le16_to_cpu

extern __u16 x;
extern __u16 y;

void foo_old(void)
{
	if (le16_to_cpu(x) > y) 
		y = x;
}