Subject: KVA usage of old-style buffers
To: None <>
From: Frank van der Linden <>
List: tech-kern
Date: 10/02/2001 00:08:11
Due to a mistake I made in the AGP code, I realized something about
the old-style buffer usage. I made the AGP code always map the graphics
aperture into kernel virtual memory, using pci_mapreg_map. This
wasn't needed, and I've corrected that.

However, I noticed that on my main system (dual Athlon, 1G of RAM),
I couldn't even map a 64MB sized graphics aperture. The i386 port
has 1G of KVM, but it turns out that, even that early in autoconfig,
64M wasn't even available anymore.

The bad guy here is the buffer code, eating up MAXBSIZE * nbuf
bytes of kva. This amounts to some 740MB on my system. This seems
to be way too much, since we now have UBC, and vfs_cluster.c
has been nuked.

I'm going to put a cap on this on the i386 port (again), but
I was wondering if this shouldn't be done for all ports.

- Frank

Frank van der Linden                 
Quality NetBSD CDs, Support & Service.