* [PATCH] x86: documentation fix regarding boot protocol
@ 2008-12-14 17:50 Philipp Kohlbecher
2008-12-15 9:22 ` Ian Campbell
2008-12-16 21:06 ` Ingo Molnar
0 siblings, 2 replies; 6+ messages in thread
From: Philipp Kohlbecher @ 2008-12-14 17:50 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin; +Cc: Ian Campbell, linux-kernel
Documentation/x86/boot.txt describes payload_offset as the offset
from the end of the real-mode code. In fact, it is more accurately
described as the offset from the beginning of the protected-mode
code, as (a) this is how it is actually calculated and (b) the padding
after the real-mode code is not included in the offset.
Signed-off-by: Philipp Kohlbecher <xt28@gmx.de>
---
Documentation/x86/boot.txt | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 83c0033..414b6fb 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -537,8 +537,8 @@ Type: read
Offset/size: 0x248/4
Protocol: 2.08+
- If non-zero then this field contains the offset from the end of the
- real-mode code to the payload.
+ If non-zero then this field contains the offset from the beginning
+ of the protected-mode code to the payload.
The payload may be compressed. The format of both the compressed and
uncompressed data should be determined using the standard magic
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] x86: documentation fix regarding boot protocol
2008-12-14 17:50 [PATCH] x86: documentation fix regarding boot protocol Philipp Kohlbecher
@ 2008-12-15 9:22 ` Ian Campbell
2008-12-15 11:27 ` Philipp Kohlbecher
2008-12-15 14:27 ` H. Peter Anvin
2008-12-16 21:06 ` Ingo Molnar
1 sibling, 2 replies; 6+ messages in thread
From: Ian Campbell @ 2008-12-15 9:22 UTC (permalink / raw)
To: Philipp Kohlbecher
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, linux-kernel
On Sun, 2008-12-14 at 18:50 +0100, Philipp Kohlbecher wrote:
> Documentation/x86/boot.txt describes payload_offset as the offset
> from the end of the real-mode code. In fact, it is more accurately
> described as the offset from the beginning of the protected-mode
> code, as (a) this is how it is actually calculated and (b) the padding
> after the real-mode code is not included in the offset.
>
> Signed-off-by: Philipp Kohlbecher <xt28@gmx.de>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
The padding after the real-mode code which you mention is just the
implicit padding because the size of the real-mode code is specified in
sectors (and hence is rounded up), isn't it?
Is it worth saying that the payload_offset is relative to (setup_sectors
+1) * 512?
>
> ---
>
> Documentation/x86/boot.txt | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
> index 83c0033..414b6fb 100644
> --- a/Documentation/x86/boot.txt
> +++ b/Documentation/x86/boot.txt
> @@ -537,8 +537,8 @@ Type: read
> Offset/size: 0x248/4
> Protocol: 2.08+
>
> - If non-zero then this field contains the offset from the end of the
> - real-mode code to the payload.
> + If non-zero then this field contains the offset from the beginning
> + of the protected-mode code to the payload.
>
> The payload may be compressed. The format of both the compressed and
> uncompressed data should be determined using the standard magic
>
--
Ian Campbell
* weasel wonders how stupid one has to be to spam alt.anonymous.messages
weasel: about half as stupid as one has to be to harvest it.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86: documentation fix regarding boot protocol
2008-12-15 9:22 ` Ian Campbell
@ 2008-12-15 11:27 ` Philipp Kohlbecher
2008-12-15 11:34 ` Ian Campbell
2008-12-15 14:27 ` H. Peter Anvin
1 sibling, 1 reply; 6+ messages in thread
From: Philipp Kohlbecher @ 2008-12-15 11:27 UTC (permalink / raw)
To: Ian Campbell; +Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, linux-kernel
Ian Campbell wrote:
> On Sun, 2008-12-14 at 18:50 +0100, Philipp Kohlbecher wrote:
>> Documentation/x86/boot.txt describes payload_offset as the offset
>> from the end of the real-mode code. In fact, it is more accurately
>> described as the offset from the beginning of the protected-mode
>> code, as (a) this is how it is actually calculated and (b) the padding
>> after the real-mode code is not included in the offset.
>>
>> Signed-off-by: Philipp Kohlbecher <xt28@gmx.de>
>
> Acked-by: Ian Campbell <ijc@hellion.org.uk>
>
> The padding after the real-mode code which you mention is just the
> implicit padding because the size of the real-mode code is specified in
> sectors (and hence is rounded up), isn't it?
Yes, it is. You can certainly view the padding as an implicit part of
the real-mode code, which is why the current statement isn't wrong --
there is simply room for improvement.
> Is it worth saying that the payload_offset is relative to (setup_sectors
> +1) * 512?
The fact that the protected-mode code starts at that address is already
mentioned under the heading "LOADING THE REST OF THE KERNEL" (where
protected mode is for some reason referred to as "non-real-mode").
(Please note that the header field is called "setup_sects", not
"setup_sectors".)
>> ---
>>
>> Documentation/x86/boot.txt | 4 ++--
>> 1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
>> index 83c0033..414b6fb 100644
>> --- a/Documentation/x86/boot.txt
>> +++ b/Documentation/x86/boot.txt
>> @@ -537,8 +537,8 @@ Type: read
>> Offset/size: 0x248/4
>> Protocol: 2.08+
>>
>> - If non-zero then this field contains the offset from the end of the
>> - real-mode code to the payload.
>> + If non-zero then this field contains the offset from the beginning
>> + of the protected-mode code to the payload.
>>
>> The payload may be compressed. The format of both the compressed and
>> uncompressed data should be determined using the standard magic
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86: documentation fix regarding boot protocol
2008-12-15 11:27 ` Philipp Kohlbecher
@ 2008-12-15 11:34 ` Ian Campbell
0 siblings, 0 replies; 6+ messages in thread
From: Ian Campbell @ 2008-12-15 11:34 UTC (permalink / raw)
To: Philipp Kohlbecher
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, linux-kernel
On Mon, 2008-12-15 at 12:27 +0100, Philipp Kohlbecher wrote:
> Ian Campbell wrote:
> > On Sun, 2008-12-14 at 18:50 +0100, Philipp Kohlbecher wrote:
> >> Documentation/x86/boot.txt describes payload_offset as the offset
> >> from the end of the real-mode code. In fact, it is more accurately
> >> described as the offset from the beginning of the protected-mode
> >> code, as (a) this is how it is actually calculated and (b) the padding
> >> after the real-mode code is not included in the offset.
> >>
> >> Signed-off-by: Philipp Kohlbecher <xt28@gmx.de>
> >
> > Acked-by: Ian Campbell <ijc@hellion.org.uk>
> >
> > The padding after the real-mode code which you mention is just the
> > implicit padding because the size of the real-mode code is specified in
> > sectors (and hence is rounded up), isn't it?
>
> Yes, it is. You can certainly view the padding as an implicit part of
> the real-mode code, which is why the current statement isn't wrong --
> there is simply room for improvement.
Agreed.
> > Is it worth saying that the payload_offset is relative to (setup_sectors
> > +1) * 512?
>
> The fact that the protected-mode code starts at that address is already
> mentioned under the heading "LOADING THE REST OF THE KERNEL" (where
> protected mode is for some reason referred to as "non-real-mode").
I'd missed/forgotten that section, I don't think anything extra is
needed then.
Ian.
--
Ian Campbell
Current Noise: Orange Goblin - Made Of Rats
Fatal Error: Found [MS-Windows] System -> Repartitioning Disk for Linux...
(By cbbrown@io.org, Christopher Browne)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86: documentation fix regarding boot protocol
2008-12-15 9:22 ` Ian Campbell
2008-12-15 11:27 ` Philipp Kohlbecher
@ 2008-12-15 14:27 ` H. Peter Anvin
1 sibling, 0 replies; 6+ messages in thread
From: H. Peter Anvin @ 2008-12-15 14:27 UTC (permalink / raw)
To: Ian Campbell
Cc: Philipp Kohlbecher, Thomas Gleixner, Ingo Molnar, linux-kernel
Ian Campbell wrote:
>
> The padding after the real-mode code which you mention is just the
> implicit padding because the size of the real-mode code is specified in
> sectors (and hence is rounded up), isn't it?
>
> Is it worth saying that the payload_offset is relative to (setup_sectors
> +1) * 512?
>
Yes, the padding is considered part of the real mode code. The phrasing
you're suggesting is probably the most unambiguous, though.
-hpa
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86: documentation fix regarding boot protocol
2008-12-14 17:50 [PATCH] x86: documentation fix regarding boot protocol Philipp Kohlbecher
2008-12-15 9:22 ` Ian Campbell
@ 2008-12-16 21:06 ` Ingo Molnar
1 sibling, 0 replies; 6+ messages in thread
From: Ingo Molnar @ 2008-12-16 21:06 UTC (permalink / raw)
To: Philipp Kohlbecher
Cc: Thomas Gleixner, H. Peter Anvin, Ian Campbell, linux-kernel
* Philipp Kohlbecher <xt28@gmx.de> wrote:
> Documentation/x86/boot.txt describes payload_offset as the offset
> from the end of the real-mode code. In fact, it is more accurately
> described as the offset from the beginning of the protected-mode
> code, as (a) this is how it is actually calculated and (b) the padding
> after the real-mode code is not included in the offset.
>
> Signed-off-by: Philipp Kohlbecher <xt28@gmx.de>
>
> ---
>
> Documentation/x86/boot.txt | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
applied to tip/x86/doc, thanks!
Ingo
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2008-12-16 21:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2008-12-14 17:50 [PATCH] x86: documentation fix regarding boot protocol Philipp Kohlbecher
2008-12-15 9:22 ` Ian Campbell
2008-12-15 11:27 ` Philipp Kohlbecher
2008-12-15 11:34 ` Ian Campbell
2008-12-15 14:27 ` H. Peter Anvin
2008-12-16 21:06 ` Ingo Molnar
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