Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains

Ingo Molnar
2001-02-05T22:10:10Z

On Mon, 5 Feb 2001, Stephen C. Tweedie wrote:

> > Obviously the disk access itself must be sector aligned and the total
> > length must be a multiple of the sector length, but there shouldn't be
> > any restrictions on the data buffers.
>
> But there are. Many controllers just break down and corrupt things
> silently if you don't align the data buffers (Jeff Merkey found this
> by accident when he started generating unaligned IOs within page
> boundaries in his NWFS code). And a lot of controllers simply cannot
> break a sector dma over a page boundary (at least not without some
> form of IOMMU remapping).

so we are putting workarounds for hardware bugs into the design?

Ingo