HEADS UP Re: cvs commit: src/sys/conf options.i386 src/sys/i386/i386 bios.c locore.s machdep.c mpboot.s pmap.c vm86bios.s vm_machdep.c src/sys/i386/include _types.h bus_at386.h param.h pmap.

Mike Silbersack silby at silby.com
Sun Mar 30 13:38:10 PST 2003

On Sun, 30 Mar 2003, Jake Burkholder wrote:

> > Do these changes allow something like a 3G KVA space without shrinking
> > processes address spaces?
> No, it doesn't make the virtual address space any bigger, it just allows
> more physical memory.  This is a bit of a problem because the tunables that
> are based on physical memory size don't scale well past 4G of ram, its easy
> to end up with may too many vnodes.

Is it practically possible with PAE and busdma'd drivers that such a
configuration could work?

> > it also be coaxed into acting in such a manner than busdma is _required_,
> > so that a 256MB i386 box can be used to see if a driver is busdma
> > compliant?
> Not really.  The best way is to buy a sparc :).  I suppose that you could
> create your dma tags such that busdma thinks it needs to bounce, this would
> at least test that you've got the right bus_dmamap_syncs. ie set lowaddr to
> below the highest physical address in your machine.

I'll give that a shot if I try to busdma a driver, thanks.

Mike "Silby" Silbersack

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