CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2021/04/03 09:59:08
Modified files:
sys/arch/arm64/dev: smmu.c
Log message:
Add a guard page between I/O virtual address space allocations. The idea
is that IOVA allocations always have a gap in-between which produces a fault
on access. If a transfer to a given allocation runs further than expected
we should be able to see it. We pre-allocate IOVA on bus DMA map creation,
and as long as we don't allocate a PTE descriptor, this comes with no cost.
We have plenty of address space anyway, so adding a page-sized gap does not
hurt at all and can only have positive effects.
Idea from kettenis@
