[Crash-utility] [PATCH] Endian-mismatch: crash shows a contrary error message

[Hu Keping]

于 2014/9/30 22:08, Dave Anderson 写道:
>
>
> ----- Original Message -----
>> When the vmcore or vmlinux is not the same endian with the host,
>> crash will give out a error message to show that mismatching, but
>> the message itself is not correct.
>> This patch fix that logical bug.
>
> Interesting -- I've never been able to actually test this until now -- with
> a ppc64/ppc64le combination.  I'm guessing you saw this on a big-endian
> 32-bit ARM?
>

Yes, the kdump file i used was generated by a network device -- a 
big-endian 32-bit ARM board.

As we all known, the network byte order is big-endian, so we chose to 
use the same byte order on the network device. Actually, almost all the 
network devices are big-endian.

Unfortunately, CRASH is not support big-endian yet. I've added some 
codes to make it to pass through the init routines and make some 
commands say, kmem -i, ps, log, etc. works.

It seems to me that you are interested about the big-endian enabled.But 
the pathes are all too rough, so I havn't sent them out yet.For example, 
when CRASH wants to use a unsigned long variable, it will first use 
readmem() to get that, what I did was just make some reverse before 
using it.

There is a discussion -- "gdb on KDUMP files" -- on the mailing list. I 
have been considering something similar with that these days.If we can 
use gdb to read the memory, the byte-order-problem will never be a 
problem again, because gdb can change byte order automatically, 
meanwhile it can change the byte order by sending a command "set endian 
big(small/auto)".

Thanks,
     Hu Keping


> Good catch -- queued for crash-7.0.9:
>
>    https://github.com/crash-utility/crash/commit/5b78ac40710048705108cbd2e44d2ddc4cf71d72
>
> Thanks,
>    Dave
>
>
>>
>> Signed-off-by: Hu Keping <hukeping at huawei.com>
>> ---
>>   tools.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools.c b/tools.c
>> index 4ff3fd5..cb684b1 100644
>> --- a/tools.c
>> +++ b/tools.c
>> @@ -5515,12 +5515,12 @@ endian_mismatch(char *file, char dumpfile_endian,
>> ulong query)
>>   	case ELFDATA2LSB:
>>   		if (__BYTE_ORDER == __LITTLE_ENDIAN)
>>   			return FALSE;
>> -		endian = "big-endian";
>> +		endian = "little-endian";
>>   		break;
>>   	case ELFDATA2MSB:
>>   		if (__BYTE_ORDER == __BIG_ENDIAN)
>>   			return FALSE;
>> -		endian = "little-endian";
>> +		endian = "big-endian";
>>   		break;
>>   	default:
>>   		endian = "unknown";
>> --
>> 1.8.5.5
>>
>>
>
> .
>