MAINTAINERS file out of date?

MAINTAINERS file out of date?

[Michael McConnell]

Hi folks,

I noticed the MAINTAINERS file still lists Riley Williams as the 
maintainer of the i386 boot code, presumably as no-one else has taken it 
up in his absence (though, I'm sure it's probably been touched since 
late 2004).

If I knew the first thing about the i386 boot process I would volunteer, 
but sadly I don't....

This article below details the reason for his absence, but please make 
sure you're sitting down before clicking. (It is work-safe.)
http://www.chorleytoday.co.uk/ViewArticle2.aspx?SectionID=81&ArticleID=905248

Sorry to be the bearer of bad news.

-- 
-- Michael "Soruk" McConnell
    Eridani Star System - http://www.eridani.co.uk/

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

Michael McConnell wrote:
> Hi folks,
> 
> I noticed the MAINTAINERS file still lists Riley Williams as the
> maintainer of the i386 boot code, presumably as no-one else has taken it
> up in his absence (though, I'm sure it's probably been touched since
> late 2004).
> 
> If I knew the first thing about the i386 boot process I would volunteer,
> but sadly I don't....
> 
> This article below details the reason for his absence, but please make
> sure you're sitting down before clicking. (It is work-safe.)
> http://www.chorleytoday.co.uk/ViewArticle2.aspx?SectionID=81&ArticleID=905248
> 

Dear.

I have considered myself as a rather unofficial maintainer of this code,
and wouldn't mind make it official now when I actually have a job which
both cares about and actually can support my upstream Linux activities,
which was a major pain for a while.

Overall, there is a lot of cleanup which really is needed in the i386
boot process; I have done some work on it already, but more is needed.

	-hpa

Re: MAINTAINERS file out of date?

[WANG Cong]

On Thu, Apr 26, 2007 at 04:13:01PM -0700, H. Peter Anvin wrote:
>Michael McConnell wrote:
>> Hi folks,
>> 
>> I noticed the MAINTAINERS file still lists Riley Williams as the
>> maintainer of the i386 boot code, presumably as no-one else has taken it
>> up in his absence (though, I'm sure it's probably been touched since
>> late 2004).
>> 
>> If I knew the first thing about the i386 boot process I would volunteer,
>> but sadly I don't....
>> 
>> This article below details the reason for his absence, but please make
>> sure you're sitting down before clicking. (It is work-safe.)
>> http://www.chorleytoday.co.uk/ViewArticle2.aspx?SectionID=81&ArticleID=905248
>> 
>
>Dear.
>
>I have considered myself as a rather unofficial maintainer of this code,
>and wouldn't mind make it official now when I actually have a job which
>both cares about and actually can support my upstream Linux activities,
>which was a major pain for a while.
>
>Overall, there is a lot of cleanup which really is needed in the i386
>boot process; I have done some work on it already, but more is needed.
>

Sounds interesting. Can you point me what needs to be done exactly? Maybe I can help you. ;)

Have fun!

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

WANG Cong wrote:
>>
>> I have considered myself as a rather unofficial maintainer of this code,
>> and wouldn't mind make it official now when I actually have a job which
>> both cares about and actually can support my upstream Linux activities,
>> which was a major pain for a while.
>>
>> Overall, there is a lot of cleanup which really is needed in the i386
>> boot process; I have done some work on it already, but more is needed.
> 
> Sounds interesting. Can you point me what needs to be done exactly? Maybe I can help you. ;)

There was a long thread on the linux-virtualization list
(@lists.linux-foundation.org) just a few days ago.  The biggest single
issue right now is probably how we transition from the bootup page
tables to the "real" init_mm page tables, but the real-mode code also
needs a massive overhaul (especially so since this code can and should
be shared with x86-64); in particular I really want to get rid of the
insane segment handling, where segments are constantly recalculated for
no good reason.

For the real-mode stuff, I have some patches already in the works for
this.  Eric W. Biederman has also done a lot of work in this area.

	-hpa

Re: MAINTAINERS file out of date?

[WANG Cong]

On Thu, Apr 26, 2007 at 06:12:43PM -0700, H. Peter Anvin wrote:
>WANG Cong wrote:
>>>
>>> I have considered myself as a rather unofficial maintainer of this code,
>>> and wouldn't mind make it official now when I actually have a job which
>>> both cares about and actually can support my upstream Linux activities,
>>> which was a major pain for a while.
>>>
>>> Overall, there is a lot of cleanup which really is needed in the i386
>>> boot process; I have done some work on it already, but more is needed.
>> 
>> Sounds interesting. Can you point me what needs to be done exactly? Maybe I can help you. ;)
>
>There was a long thread on the linux-virtualization list
>(@lists.linux-foundation.org) just a few days ago.  The biggest single
>issue right now is probably how we transition from the bootup page
>tables to the "real" init_mm page tables, but the real-mode code also
>needs a massive overhaul (especially so since this code can and should
>be shared with x86-64); in particular I really want to get rid of the
>insane segment handling, where segments are constantly recalculated for
>no good reason.
>
>For the real-mode stuff, I have some patches already in the works for
>this.  Eric W. Biederman has also done a lot of work in this area.
>
>	-hpa

Thanks for your point. 
I know little about virtualization, maybe can't help much. But I am interested in other things you mentioned. AFAIK, segments can't be avoided on i386, and Linux uses them very little, how are they recalculated constantly?

Regards!

Re: MAINTAINERS file out of date?

[Eric W. Biederman]

WANG Cong <xiyou.wangcong@gmail.com> writes:

>
> Thanks for your point. 
> I know little about virtualization, maybe can't help much. But I am interested
> in other things you mentioned. AFAIK, segments can't be avoided on i386, and
> Linux uses them very little, how are they recalculated constantly?

Look in arch/i386/boot/setup.S it runs in 16bit mode.  We are talking about
real mode segments not 16bit segments.

16bit real mode is a completely different ball game, and why we keep BIOS
calls isolated to that one dinky file.

Eric

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

Eric W. Biederman wrote:
> WANG Cong <xiyou.wangcong@gmail.com> writes:
> 
>> Thanks for your point. 
>> I know little about virtualization, maybe can't help much. But I am interested
>> in other things you mentioned. AFAIK, segments can't be avoided on i386, and
>> Linux uses them very little, how are they recalculated constantly?
> 
> Look in arch/i386/boot/setup.S it runs in 16bit mode.  We are talking about
> real mode segments not 16bit segments.
> 
> 16bit real mode is a completely different ball game, and why we keep BIOS
> calls isolated to that one dinky file.
> 

A lot of that code (although, of course, not all) could be written in C,
though.  I'm thinking of taking a stab at rewriting it that way.

	-hpa

Re: MAINTAINERS file out of date?

[Eric W. Biederman]

"H. Peter Anvin" <hpa@zytor.com> writes:

> A lot of that code (although, of course, not all) could be written in C,
> though.  I'm thinking of taking a stab at rewriting it that way.

Is this using the .code16gcc?  Or are you thinking of some other
technique.  Requiring another C compiler to build the kernel would
be a pain to use.

Eric

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

Eric W. Biederman wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
> 
>> A lot of that code (although, of course, not all) could be written in C,
>> though.  I'm thinking of taking a stab at rewriting it that way.
> 
> Is this using the .code16gcc?  Or are you thinking of some other
> technique.  Requiring another C compiler to build the kernel would
> be a pain to use.

.code16gcc was what I was using.  There is a GSoC project that I'm
mentoring to get 16-bit support for gcc, that will be possible to
eventually migrate to (for code size) if/when it gets implemented and
gets pushed out far enough, but that's for the future.

	-hpa

Re: MAINTAINERS file out of date?

[WANG Cong]

On Thu, Apr 26, 2007 at 10:27:47PM -0700, H. Peter Anvin wrote:
>Eric W. Biederman wrote:
>> "H. Peter Anvin" <hpa@zytor.com> writes:
>> 
>>> A lot of that code (although, of course, not all) could be written in C,
>>> though.  I'm thinking of taking a stab at rewriting it that way.
>> 
>> Is this using the .code16gcc?  Or are you thinking of some other
>> technique.  Requiring another C compiler to build the kernel would
>> be a pain to use.
>
>.code16gcc was what I was using.  There is a GSoC project that I'm
>mentoring to get 16-bit support for gcc, that will be possible to
>eventually migrate to (for code size) if/when it gets implemented and
>gets pushed out far enough, but that's for the future.
>
>	-hpa

Thanks! I will take a look at that file.

Maybe we can rewrite them in C, use a 16-bit C compiler to generate AT&T asm code and finally push the asm code in the kernel source tree. But perhaps there is no such ideal compiler. ;)

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

WANG Cong wrote:
> On Thu, Apr 26, 2007 at 10:27:47PM -0700, H. Peter Anvin wrote:
> 
> Thanks! I will take a look at that file.
> 
> Maybe we can rewrite them in C, use a 16-bit C compiler to generate AT&T asm code and finally push the asm code in the kernel source tree. But perhaps there is no such ideal compiler. ;)
> 

No, that would be bad.

	-hpa

Re: MAINTAINERS file out of date?

[Andi Kleen]

> 
> A lot of that code (although, of course, not all) could be written in C,
> though.  I'm thinking of taking a stab at rewriting it that way.

That would require a new compiler, right? I don't think that would
make users very happy.

Besides the code is not exactly that maintenance intensive and only
changes rarely so I don't need a pressing need to rewrite it

-Andi
 

Re: MAINTAINERS file out of date?

[H. Peter Anvin]

Andi Kleen wrote:
>> A lot of that code (although, of course, not all) could be written in C,
>> though.  I'm thinking of taking a stab at rewriting it that way.
> 
> That would require a new compiler, right? I don't think that would
> make users very happy.
> 
> Besides the code is not exactly that maintenance intensive and only
> changes rarely so I don't need a pressing need to rewrite it

No, it would not need a new compiler.  All it requires is gcc plus a
reasonably recent binutils which you need anyway.

	-hpa

Re: MAINTAINERS file out of date?

[Eric W. Biederman]

"H. Peter Anvin" <hpa@zytor.com> writes:

> Andi Kleen wrote:
>>> A lot of that code (although, of course, not all) could be written in C,
>>> though.  I'm thinking of taking a stab at rewriting it that way.
>> 
>> That would require a new compiler, right? I don't think that would
>> make users very happy.
>> 
>> Besides the code is not exactly that maintenance intensive and only
>> changes rarely so I don't need a pressing need to rewrite it
>
> No, it would not need a new compiler.  All it requires is gcc plus a
> reasonably recent binutils which you need anyway.

There opportunities to enhance this code without writing it in C.
Such as building the code out comprehensible single of subroutines,
with a well defined calling sequence.

The big benefit when you can go to C is that you can include headers
from elsewhere in the kernel and since setup.S is increasingly
becoming optional it has a fixed interface to the rest of
the kernel, so there is much less opportunity for enhancement there.

Eric