Broken A20 gate handling

Broken A20 gate handling

[Ludovic Drolez]

Hi !

Recently I tried to use grub(2) with a compaq evo D510. These boxes do not seem 
to have a keyboard controller, so grub freeze in gatea20().

Most free bootloaders fail, but one is okay: syslinux/isolinux.

I've taken a look at syslinux's code, and indeed A20 activation is done much 
more carefully than in grub, and more tricks are used.

I think it's really important to fix grub's code (by stealing code from isolinux 
?), because more and more PCs without a good old keyboard controller will hit 
the market.

Are there any plans to improve gatea20() ? (Moreover, grub2's code for gatea20 
is even worse than grub-legacy)

Regards,

-- 
Ludovic DROLEZ

Re: Broken A20 gate handling

[Ludovic Drolez]

Ludovic Drolez wrote:
> I think it's really important to fix grub's code (by stealing code from 
> isolinux ?),

Also, I've just found that for the linux kernel, they also used sys/isolinux's code.

Cheers,

    Ludovic DROLEZ

Re: Broken A20 gate handling

[Marco Gerards]

Ludovic Drolez <ldrolez@linbox.com> writes:

> Ludovic Drolez wrote:
>> I think it's really important to fix grub's code (by stealing code
>> from isolinux ?),
>
> Also, I've just found that for the linux kernel, they also used
> sys/isolinux's code.

Didn't syslinux/isolinux use linux code?

I think it is not possible for us to use syslinux/isolinux code I
think.  For GRUB the copyrights need to be assigned to the FSF before
a patch can be applied.  But we can write code to fix this problem
ourselves, hopefully someone will send in a patch for this.

--
Marco

Re: Broken A20 gate handling (about GPL)

[Ludovic Drolez]

Marco Gerards wrote:
> I think it is not possible for us to use syslinux/isolinux code I
> think.  For GRUB the copyrights need to be assigned to the FSF before
> a patch can be applied. 

!?!?!?

There's no such requirement in the GNU GPL ! (and syslinux is GPLed)

If collaborative work is impossible with grub, then grub is not licensed under 
the GPL.

Ludovic DROLEZ

Re: Broken A20 gate handling (about GPL)

[Hollis Blanchard]

On Jul 1, 2005, at 7:43 AM, Ludovic Drolez wrote:

> Marco Gerards wrote:
>> I think it is not possible for us to use syslinux/isolinux code I
>> think.  For GRUB the copyrights need to be assigned to the FSF before
>> a patch can be applied.
>
> !?!?!?
>
> There's no such requirement in the GNU GPL ! (and syslinux is GPLed)
>
> If collaborative work is impossible with grub, then grub is not  
> licensed under the GPL.

It's not about the GPL, it's about FSF projects:  
http://www.gnu.org/prep/maintain/html_node/Copyright- 
Papers.html#Copyright-Papers

Yes, it is a real pain, and inhibits development, which is true with  
most lawyerly things.

-Hollis

Re: Broken A20 gate handling (about GPL)

[Yoshinori K. Okuji]

Hello Ludovic,

On Friday 01 July 2005 14:43, Ludovic Drolez wrote:
> Marco Gerards wrote:
> > I think it is not possible for us to use syslinux/isolinux code I
> > think.  For GRUB the copyrights need to be assigned to the FSF before
> > a patch can be applied.
>
> !?!?!?

I am afraid that Marco misunderstood this.

We prefer assigning copyright to the FSF, but this does not mean that we may 
not use others' code. The important thing is that we must carefully treat who 
owns which code, so we must separate code into different files when we reuse 
code written for other projects.

This is only _my preference_, but I would like to keep critical parts of GRUB 
owned solely by the FSF. So, for example, I do not care about the copyright 
of a filesystem very much, but I do care about the copyright of bootstrap 
code.

In the case of the A20, I'm not sure how I want to implement it. It is not 
that bad to use syslinux code, because we have our own alternative. However, 
this code is very critical, and I prefer writing our own code. After all, my 
opinion looks like the same as Marco. :p

> There's no such requirement in the GNU GPL ! (and syslinux is GPLed)
> 
> If collaborative work is impossible with grub, then grub is not licensed
> under the GPL.

This is not related to GPL. GPL is just a license. It does not define how a 
project should be managed.

Okuji

Re: Broken A20 gate handling (about GPL)

[Ludovic Drolez]

Yoshinori K. Okuji wrote:
> In the case of the A20, I'm not sure how I want to implement it. It is not 
> that bad to use syslinux code, because we have our own alternative. However, 
> this code is very critical, and I prefer writing our own code. After all, my 
> opinion looks like the same as Marco. :p

Yes this code is critical, as you see flaws in this code makes grub unusable on 
new PCs (freeze without *any* error message). Since it's the most critical part 
of grub, why simply not use the most stable code available for A20 handling: the 
linux kernel ?

Moreover, IMHO, it makes no sense trying to rewrite such low level functions, 
since there are not hundreds ways of writing it !

Cheers,

-- 
Ludovic DROLEZ

Re: Broken A20 gate handling (about GPL)

[Yoshinori K. Okuji]

On Friday 01 July 2005 19:01, Ludovic Drolez wrote:
> Yes this code is critical, as you see flaws in this code makes grub
> unusable on new PCs (freeze without *any* error message). Since it's the
> most critical part of grub, why simply not use the most stable code
> available for A20 handling: the linux kernel ?

Because I do not trust the copyright management in Linux at all.

You must understand that we are volunteers. We very much prefer not being sued 
to taking risk only for your computer. You say "new PCs", but this wording is 
too brave. It is only with the braindead Compaq computer.

> Moreover, IMHO, it makes no sense trying to rewrite such low level
> functions, since there are not hundreds ways of writing it !

So? Does anything prevent you from writing your own code?

Okuji

Re: [Bulk] Re: Broken A20 gate handling (about GPL & FSF copyright assignment)

[Vincent Pelletier]

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Ludovic Drolez wrote:
> Moreover, IMHO, it makes no sense trying to rewrite such low level
> functions, since there are not hundreds ways of writing it !

There are at least 2 ways :
1) copy-paste code
2) read specs, implement them - following the directions FSF paper gives.

The result might be the same code, but the way to get it matters too.

Vincent Pelletier

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Re: Broken A20 gate handling (about GPL)

[Marco Gerards]

"Yoshinori K. Okuji" <okuji@enbug.org> writes:

> We prefer assigning copyright to the FSF, but this does not mean that we may 
> not use others' code. The important thing is that we must carefully treat who 
> owns which code, so we must separate code into different files when we reuse 
> code written for other projects.
>
> This is only _my preference_, but I would like to keep critical parts of GRUB 
> owned solely by the FSF. So, for example, I do not care about the copyright 
> of a filesystem very much, but I do care about the copyright of bootstrap 
> code.
>
> In the case of the A20, I'm not sure how I want to implement it. It is not 
> that bad to use syslinux code, because we have our own alternative. However, 
> this code is very critical, and I prefer writing our own code. After all, my 
> opinion looks like the same as Marco. :p

I am sorry that I confused some of you.  My answer was not that clear,
hopefully with this reply it is a bit clearer.

The FSF makes a clear distinction.  In the case of a library or so it
can be integrated, like it was done with LZO.  The A20 code is not a
library.  To put a lot of code from all kinds of projects in separate
files is not what I prefer.

Thanks,
Marco

Re: Broken A20 gate handling

[Ludovic Drolez]

Marco Gerards wrote:
> 
> Didn't syslinux/isolinux use linux code?
> 
I don't think so, in setup.S you can read:

*
  * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
  * by Robert Schwebel, December 2001 <robert@schwebel.de>
  */


-- 
Ludovic DROLEZ

Re: Broken A20 gate handling

[Peter Jones]

On Fri, 2005-07-01 at 12:35 +0200, Marco Gerards wrote:
> Ludovic Drolez <ldrolez@linbox.com> writes:
> 
> > Ludovic Drolez wrote:
> >> I think it's really important to fix grub's code (by stealing code
> >> from isolinux ?),
> >
> > Also, I've just found that for the linux kernel, they also used
> > sys/isolinux's code.
> 
> Didn't syslinux/isolinux use linux code?

From setup.S:
# A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.

That being said, he was certainly heavily involved in the Linux parts of
that anyway.
-- 
        Peter