Re: the new VMt [4MB+ blocks]

Matti Aarnio
2000-09-25T19:03:01Z

On Mon, Sep 25, 2000 at 06:06:11PM +0100, Alan Cox wrote:
> > > > Stupidity has no limits...
> > > Unfortunately its frequently wired into the hardware to save a few cents on
> > > scatter gather logic.
> >
> > Since when hardware folks became exempt from the rule above? 128K is
> > almost tolerable, there were requests for 64 _mega_bytes...
>
> Most cheap ass PCI hardware is built on the basis you can do linear 4Mb
> allocations. There is a reason for this. You can do that 4Mb allocation on
> NT or Windows 9x

Sure, but intel processors have this neat 4 MB "super-page"
feature in the MMU... (as we all well know)

Sometimes allocating such monster memory blocks could be supported,
but it should not be expected to be *fast*. E.g. if doing it in
"reliable" way needs possibly moving currently allocated pages
away from memory to create such a hole(s), so be it..

Anybody here who can describe those M$ API calls ?
Are they kernel/DDK-only, or userspace ones, or both ?

/Matti Aarnio