On September 26, 2019 12:55:51 AM PDT, Cao jin <caoj.fnst@xxxxxxxxxxxxxx> wrote:
>On 9/26/19 2:01 PM, Ingo Molnar wrote:
>> * Cao jin <caoj.fnst@xxxxxxxxxxxxxx> wrote:
>>
>>> The fields marked with (reloc) actually are not dedicated for
>writing,
>>> but communicating info for relocatable kernel with boot loaders. For
>>> example:
>>>
>>> ============ ============
>>> Field name: pref_address
>>> Type: read (reloc)
>>> Offset/size: 0x258/8
>>> Protocol: 2.10+
>>> ============ ============
>>>
>>> ============ ========================
>>> Field name: code32_start
>>> Type: modify (optional, reloc)
>>> Offset/size: 0x214/4
>>> Protocol: 2.00+
>>> ============ ========================
>>>
>>> Signed-off-by: Cao jin <caoj.fnst@xxxxxxxxxxxxxx>
>>> ---
>>> Unless I have incorrect non-native understanding for "fill in", I
>think
>>> this is inaccurate.
>>>
>>> Documentation/x86/boot.rst | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/x86/boot.rst b/Documentation/x86/boot.rst
>>> index 08a2f100c0e6..a611bf04492d 100644
>>> --- a/Documentation/x86/boot.rst
>>> +++ b/Documentation/x86/boot.rst
>>> @@ -243,7 +243,7 @@ bootloader ("modify").
>>>
>>> All general purpose boot loaders should write the fields marked
>>> (obligatory). Boot loaders who want to load the kernel at a
>>> -nonstandard address should fill in the fields marked (reloc); other
>>> +nonstandard address should consult with the fields marked (reloc);
>other
>>> boot loaders can ignore those fields.
>>>
>>> The byte order of all fields is littleendian (this is x86, after
>all.)
>>
>> Well, this documentation is written from the point of view of a
>> *bootloader*, not the kernel. So the 'fill in' says that the
>bootloader
>> should write those fields - which is correct, right?
>>
>
>Take pref_address or relocatable_kernel for example, they have type:
>read (reloc), does boot loader need to write them? I don't see grub
>does
>this at least.
Read means the boot later reads them.
--
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