2005-09-23 07:49:44

by Franck Bui-Huu

Subject: How to add a new ram region ?

Hi,

I'm working on port of linux 2.6.13. The target is a custom board
based on a MIPS cpu. There are several RAMs on this board whose
address are not contiguous and don't start to 0 . I currently succeed
to make linux detect one of these RAM (the biggest one) but I'd like
to make linux able to use the others...I'd like to use the other in a
particular way: I would like to be able to allocate memory only on a
single RAM when needed in kernel space, and in userspace I would be
able to export a RAM disk that uses memory on a single RAM.

Could someone tell me how to do that or give me some pointers ?

Thanks
--
Franck

2005-09-23 22:59:17

by Randy Dunlap

Subject: Re: How to add a new ram region ?

On Fri, 23 Sep 2005 09:49:43 +0200 Franck wrote:

> Hi,
>
> I'm working on port of linux 2.6.13. The target is a custom board
> based on a MIPS cpu. There are several RAMs on this board whose
> address are not contiguous and don't start to 0 . I currently succeed
> to make linux detect one of these RAM (the biggest one) but I'd like
> to make linux able to use the others...I'd like to use the other in a
> particular way: I would like to be able to allocate memory only on a
> single RAM when needed in kernel space, and in userspace I would be
> able to export a RAM disk that uses memory on a single RAM.
>
> Could someone tell me how to do that or give me some pointers ?

You can try the "memmap=" kernel boot options, although I don't
know if or how well they apply to MIPS. Some of them apparently
do apply, according to Documentation/kernel-parameters.txt .

---
~Randy
You can't do anything without having to do something else first.
-- Belefant's Law

2005-09-26 08:08:49

by Franck Bui-Huu

Subject: Re: How to add a new ram region ?

Hi Randy,

2005/9/24, Randy.Dunlap <[email protected]>:
> On Fri, 23 Sep 2005 09:49:43 +0200 Franck wrote:
>
> > Hi,
> >
> > I'm working on port of linux 2.6.13. The target is a custom board
> > based on a MIPS cpu. There are several RAMs on this board whose
> > address are not contiguous and don't start to 0 . I currently succeed
> > to make linux detect one of these RAM (the biggest one) but I'd like
> > to make linux able to use the others...I'd like to use the other in a
> > particular way: I would like to be able to allocate memory only on a
> > single RAM when needed in kernel space, and in userspace I would be
> > able to export a RAM disk that uses memory on a single RAM.
> >
> > Could someone tell me how to do that or give me some pointers ?
>
> You can try the "memmap=" kernel boot options, although I don't
> know if or how well they apply to MIPS. Some of them apparently
> do apply, according to Documentation/kernel-parameters.txt .
>

I looked at this kernel boot option and it seems that every given RAM
regions cannot be used separetly: once they're registered, I can't
allocate a page for a given region. Is that correct ?

Thanks
--
Franck