Re: 2.1.111: IDE DMA disabled...BLAH...BLAH...

Linus Torvalds (
Wed, 29 Jul 1998 12:27:38 -0700 (PDT)

On Wed, 29 Jul 1998, Mark Lord wrote:
> Yet, for some inexplicable reason, Linux continues to default
> to "external cache == ON" on all systems, when it would be a
> heck of a lot better off to disable caches at boot time.
> After all, a user-level utility could easily be written (with
> kernel hooks) to turn the caches on after booting, if safe to do so.

Umm. The difference between "cache on" and "cache off" is a bit more
drastic than "use DMA for IDE" and "don't use DMA for IDE", wouldn't you

You can test it if you wish.

The point being that a system that has cache problems is just terminally
ill, while a system with DMA problems might be fixable. Fixable by having
a list of known bad disk or BIOS vendors, for example.

Which, btw, is what I've been asking for all the time.


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