[LinuxBIOS] about make LinuxBIOS 64bit for Opteron

[Lu, Yinghai]

I'm thinking to make LinuxBIOS to run at 64 bit mode so
it can access 40 bit address in one instruction

we just need to 
1. change entry32.inc to entry64.inc...
2. change secondary.S to support 64 bit
3. change most code32 to code64

The problem is that we may need make Etherboot and mkelfImage to support
64 bit too...

how do you think about it?

YH

[Ronald G Minnich]

Lu, Yinghai wrote:
> I'm thinking to make LinuxBIOS to run at 64 bit mode so
> it can access 40 bit address in one instruction
>
> we just need to
> change entry32.inc to entry64.inc...
> change secondary.S to support 64 bit
> change most code32 to code64
>
> The problem is that we may need make Etherboot and mkelfImage to support
> 64 bit too...
>
> how do you think about it?
>
> YH

I think we have to do it.

That said, BEFORE this effort starts, I want to make sure that EVERY 
SINGLE OPTERON TARGET works as well as it did 6 months ago. And, 
currently, I don't think that is the case -- see ward's letter.

We need to get this code base back to being more solid than it currently is.

thanks

ron

[Stefan Reinauer]

* Ronald G Minnich  [051216 19:35]:
> I think we have to do it.
>
> That said, BEFORE this effort starts, I want to make sure that EVERY 
> SINGLE OPTERON TARGET works as well as it did 6 months ago. And, 
> currently, I don't think that is the case -- see ward's letter.
>
> We need to get this code base back to being more solid than it currently is.

I fully agree. We should make a feature freeze and only let changes in
that fix something until we _verified_ that all (K8) mainboards are
working and on the same level (ie. equal cmos layouts, dual core, car
enabled, etc pp.)

One step at a time. We just recovered.

Besides that, 64bit is a must, no doubt.

Stefan

Ronald G Minnich  writes:
> Lu, Yinghai wrote:
> > I'm thinking to make LinuxBIOS to run at 64 bit mode so
> > it can access 40 bit address in one instruction
> > we just need to 1. change entry32.inc to entry64.inc...
> > 2. change secondary.S to support 64 bit
> > 3. change most code32 to code64
> > The problem is that we may need make Etherboot and mkelfImage to support
> > 64 bit too...
> > how do you think about it?
> > YH

Given the other objections and the fact that PAE mode allows
you to access any address you want by changing the page table.
I think we need a justification for doing more.

As for Etherboot and mkelfImage.  Etherboot can already load a 64bit
payload.  Basically just make the ELF loader capable of handling
a 32bit or a 64bit target.

Can you really put a page table in the cache and have it work?

Eric

[Kevin O'Connor]

On Fri, Dec 16, 2005 at 04:42:53PM -0700, Eric W. Biederman wrote:
> > Lu, Yinghai wrote:
> > > The problem is that we may need make Etherboot and mkelfImage to support
> > > 64 bit too...
>
> As for Etherboot and mkelfImage.  Etherboot can already load a 64bit
> payload.  Basically just make the ELF loader capable of handling
> a 32bit or a 64bit target.

If linuxbios uses 64bit mode, does that mean the payload must be
64bit?

Is it possible to put the opteron back into 32-bit mode (for example
with a cpu reset followed by a warm-reset check at linuxbios start)?

-Kevin

[yhlu]

We can exit from 64bit....and don't need to warmrest.

in 64bit need one 4k page table level 4. I don't if we can put that in
cache at Cache as ram stage...., will try it some time several month
later..

YH

On 12/17/05, Kevin O'Connor  wrote:
> On Fri, Dec 16, 2005 at 04:42:53PM -0700, Eric W. Biederman wrote:
> > > Lu, Yinghai wrote:
> > > > The problem is that we may need make Etherboot and mkelfImage to support
> > > > 64 bit too...
> >
> > As for Etherboot and mkelfImage.  Etherboot can already load a 64bit
> > payload.  Basically just make the ELF loader capable of handling
> > a 32bit or a 64bit target.
>
> If linuxbios uses 64bit mode, does that mean the payload must be
> 64bit?
>
> Is it possible to put the opteron back into 32-bit mode (for example
> with a cpu reset followed by a warm-reset check at linuxbios start)?
>
> -Kevin

[Stefan Reinauer]

* Lu, Yinghai  [051216 19:12]:
> The problem is that we may need make Etherboot and mkelfImage to support
> 64 bit too...

or make openbios 64bit on amd64 systems. this would make a lot of sense.