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SubjectRe: sg regression in 2.6.16-rc5
Linus Torvalds wrote:
> For example, I think the IDE driver defaults to a maximum transfer of 256
> sectors, and the same number of max scatter-gather entries. Some
> controllers will actually lower that, due to silly hw problems.

Yep. Just to be specific:

256 max sectors IDE driver, 200 max sectors libata (due to driver not
hardware).

256 max s/g entries hardware limit, but due to a IOMMU merging worst
case libata (IDE driver too?) winds up with a 128 entry practical limit.

Newer SATA controllers eliminate the s/g entry limit and DMA boundary
limits, but its still 256 max-sectors for ATAPI (64k for LBA48 ATA).

Jeff


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