Re: Toshiba 64M limit and slram (was Toshiba ToPIC developer info)

[Ryan Underwood <nemesis-lists@icequake.net>]

On Wed, Jun 22, 2005 at 10:16:21AM +0100, Russell King wrote:
> 
> Unfortunately, the kernel needs to know how much RAM you really have so
> it can properly allocate memory resources.  Lying to it (by passing mem=)
> is generally a recipe for disaster.

I was under the impression that using the mem= parameter simply
truncated the high memory area, so the kernel would behave as if you
only had that amount of memory installed.

> However, if slram is making use of some area of memory, it really should
> reserve it.  That's a slram bug - please report it to the mtd mailing
> list.

I will do so.  However, it seems impossible for slram to reserve i.e.
64M-160M area unless the kernel is disallowed from using it for other
reasons.  Surely something would be allocated there already by the
time slram was activated.

> Even with slram fixed, there remains the danger of something trying to
> allocate a resource _before_ slram claims its resource...  I just hate
> the entire mem= mess entirely for this very reason.  It's completely
> unsafe.

What is the best thing to do then?  Ever since slram was designed, it
has assumed that the user would set the mem= option appropriately.  I've
had the 'reserve' option pointed to me but not tried it yet.

-- 
Ryan Underwood, <nemesis@icequake.net>