On Mon, Sep 10, 2007 at 05:11:23PM +0300, Boaz Harrosh wrote: > > In motivation to abstract scsi_cmnd members and insulate > drivers/transports from scsi_cmnd internals. The last > place left was the REQUEST_SENSE sequence when done > synchronous, by drivers.
This probably isn't serious, but I noticed one thing (beyond what Alan's
analysis noted)...
I've always assumed that the scatterlist structs passed to an HCD were,
themselves, allocated from DMA-able memory. That is, not just the transfer
buffers themselves, but the struct scatterlist also.
In this implementation, the struct scatterlist used for the single-element
transfer of the request sense buffer is part of the
struct scsi_eh_save_cmnd_info, which is allocated on the stack (for at
least usb-storage). And, stack isn't DMA-able on all arches.
It is not a problem for usb-storage, since the struct scatterlists are
processed in code into a series of URBs, so nobody actually does DMA the
scatterlist structures. However, I don't know enough about the other HCDs
to be certain about them.
Matt
--
Matthew Dharm Home: [EMAIL PROTECTED]
Maintainer, Linux USB Mass Storage Driver
Now payink attention, please. This is mouse. Click-click. Easy to
use, da? Now you try...
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User Friendly, 10/11/1998
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