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SubjectRe: [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high
On 11/22/2012 12:50 PM, H. Peter Anvin wrote:
> On 11/22/2012 12:18 PM, Yinghai Lu wrote:
>>>
>>> If we can get the sentinel hack to work that would probably be
>>> useful, but
>>> we need to understand the exact pathology.
>>
>> for kexec bzImage --real-mode-entry, code after setup_header will be
>> executed.
>>
>> so we could clear value before setup_header after copy 16bit section
>> from bzImage...
>>
>> Index: kexec-tools/kexec/arch/i386/kexec-bzImage.c
>> ===================================================================
>> --- kexec-tools.orig/kexec/arch/i386/kexec-bzImage.c
>> +++ kexec-tools/kexec/arch/i386/kexec-bzImage.c
>> @@ -212,6 +212,16 @@ int do_bzImage_load(struct kexec_info *i
>> setup_size = kern16_size + command_line_len +
>> PURGATORY_CMDLINE_SIZE;
>> real_mode = xmalloc(setup_size);
>> memcpy(real_mode, kernel, kern16_size);
>> + /*
>> + * clear value before header
>> + * not not clear value after header, --real-mode-entry
>> + * need code after header.
>> + */
>> + memset(real_mode, 0, 0x1f1);
>> + if (!real_mode_entry) {
>> + /* clear value after setup_header */
>> + memset((unsigned char *)real_mode + 0x290, 0, kern16_size -
>> 0x290);
>> + }
>>
>
> You really should move the memset() into the if() clause as well...
> doesn't matter at the moment, but that is the protocol.
>
> The limit is 0x280, not 0x290, or -- better -- you can use the byte at
> 0x201 to get the size.
>

Not doing so would be wrong, in fact.


--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.



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