Re: Strange interrupt behaviour

David S. Miller (davem@dm.cobaltmicro.com)
Sat, 11 Jul 1998 22:03:21 -0700


From: Andi Kleen <ak@muc.de>
Date: 12 Jul 1998 05:48:36 +0200

One proposal included using vmalloc() for the stack, but this was
put down because lots of drivers seem to break with that. They put
DMA buffers on the stack which might not work when they happen to
lie on the border between the two pages. This would probably
cause lots of hard-to-find, difficult-to-reporduce bugs.

My opinion is that drivers which do such things are the bits which are
broken.

Actually, the vmalloc() idea was shot down (at least by me and a few
others) for performance reasons. Every fork on SMP would then cause a
cpu cross call to all cpus to invalidate their tlb's, this would be on
every architecture, not just Intel.

Later,
David S. Miller
davem@dm.cobaltmicro.com

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