On 09/05/2013 04:48 PM, WANG Chao wrote:
> On 08/05/13 at 01:35pm, Vivek Goyal wrote:
>> I think struct x86_linux_param_header should be packed. Strange that we
>> did not do it so far.
>>
>> Without packing struct size was 3824 (decimal) on my x86_64 machine. With
>> packing it is 3820. I think there was a padding of 4 bytes at the end. So
>> it should be harmless.
>>
>> I tried to introduce more fields and that introduced padding in the
>> middle of structure and kexec stopped working and that's how I got to
>> know that bootparam is not packed.
>
> In this case that's true and x86_linux_param_header should be packed.
>
> One more thing is,
> in include/x86/x86-linux.h, we already define PACKED macro:
> #define PACKED __attribute__((packed))
> But within x86-linux.h, both PACKED_and __attribute__((packed)) are used.
>
> PACKED isn't used much time and __attribute__((packed)) is quite simple
> and straightforward. Maybe it's time we can remove the macro and use
> __attribute__((packed)) directly.
>
> I can send another patch to address this if anyone thinks it's a good
> idea.
Unifying this should be OK, I think.
>
> Thanks
> WANG Chao
>
>> ---
>> include/x86/x86-linux.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Index: kexec-tools/include/x86/x86-linux.h
>> ===================================================================
>> --- kexec-tools.orig/include/x86/x86-linux.h 2013-08-05 13:28:33.999338740 -0400
>> +++ kexec-tools/include/x86/x86-linux.h 2013-08-05 13:28:46.616475104 -0400
>> @@ -198,7 +198,7 @@ struct x86_linux_param_header {
>> struct edd_info eddbuf[EDDMAXNR]; /* 0xd00 */
>> /* 0xeec */
>> #define COMMAND_LINE_SIZE 2048
>> -};
>> +} __attribute__ ((packed));
>>
>> struct x86_linux_faked_param_header {
>> struct x86_linux_param_header hdr; /* 0x00 */
>>
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>
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>
--
Thanks.
Zhang Yanfei
