Re: Problems with too much memory (?)

Matthew Kirkwood (
Sat, 26 Apr 1997 23:01:29 +0100 (BST)

On Sat, 26 Apr 1997, Ingo Molnar wrote:

> > > MB is propably the cause... but anyway why doesn't Linux support
> > > non-cached ram... too complex and/or not worth it? ('swapping' to
> > > non-cached ram should still be quite a bit faster than swapping to
> > > harddisk)
> >
> > Some people have been known to hack the RAMdisk driver to get a RAM
> > disk in non-cached memory; then swap to the RAMdisk. This seems to
> > work, but I've never seen it supported in the official RAMdisk driver.
> btw, this should be fairly easy with a recent kernel, if i'm not missing
> something. Use mem=less_by_16M to boot with a certain amount of physical
> memory less, then use ioremap_nocache() to grab that memory (people might
> want to add a boot option, say nocache_ramdisk=16) ...

Here's one for all of the electronic engineers among you...

An ISA (or otherwise) expansion board with 30-pin SIMM sockets. I'm sure
that I'm not the only one who has a stack of old, slow 30-pin SIMMs spare,
and I rather like the idea of being able to use them as swap, or as a
secondary buffer of some sort. My (basically single-user) machine has
64Mb, which means that it only swaps when I tell it to do so :-), but a
board for 20 quid which would give me an extra 16Mb buffer before swap was
required would assist quite a number of people, I imagine.

Similarly, if I were to have any spare 70ns RAM, it would be nice to use
it profitably, if I were reluctant to put it in my machine and have to
turn all the clock settings down to 70ns from my nice 60ns EDO settings.

Does anyone reckon that this could be done cheaply and easily?

Either way, it's just a suggestion. <fx: dons asbestos jacket>


Matthew Kirkwood  |  Mail:
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