linux-kernel - Re: [RFC PATCH] x86/doc/boot_protocol: Correct the description of "reloc"

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Message-ID: <4CCDD087-62A6-4524-AD3E-6A6FD2D70FE7@zytor.com>
Date:   Thu, 26 Sep 2019 12:17:34 -0700
From:   hpa@...or.com
To:     Randy Dunlap <rdunlap@...radead.org>,
        Cao jin <caoj.fnst@...fujitsu.com>,
        Ingo Molnar <mingo@...nel.org>
CC:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, corbet@....net
Subject: Re: [RFC PATCH] x86/doc/boot_protocol: Correct the description of "reloc"

On September 26, 2019 8:20:28 AM PDT, Randy Dunlap <rdunlap@...radead.org> wrote:
>On 9/26/19 12:58 AM, hpa@...or.com wrote:
>> On September 26, 2019 12:55:51 AM PDT, Cao jin
><caoj.fnst@...fujitsu.com> wrote:
>>> On 9/26/19 2:01 PM, Ingo Molnar wrote:
>>>> * Cao jin <caoj.fnst@...fujitsu.com> 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@...fujitsu.com>
>>>>> ---
>>>>> 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.
>
>is that          boot loader ??

Yes, stupid autocorrect.
-- 
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