Re: [linux-usb-devel] Re: "sr: unaligned transfer" in 2.5.2-pre1

Matthew Dharm
2001-12-31T22:55:26Z

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Jens --

Thanks for the info. It may have been discussed 'here' (tho, this is
crosposted to two different lists), but I've been focused on 2.4 bugs (one
more left!) and hadn't seen this item.

I think for the first 2.5 kernels, we'll o with your 'vaddr' line, but I
think that being able to set highmem_io is a worthwhile thing. Which leads
me to two questions:
(1) Do the USB HCDs support highmem? I seem to recall they do, but I'm not
certain.
(2) How do I pass a highmem address to the HCDs? The URB structures we use
don't seem particularly well-suited for this.

Matt

On Mon, Dec 31, 2001 at 12:51:57PM +0100, Jens Axboe wrote:
> On Sun, Dec 30 2001, Matthew Dharm wrote:
> > If it shouldn't be used, it should be removed from the structure to force
> > people to change.
>
> It will be soonish. Davem has practically finished this already.
>
> > This is probably why usb-storage broke, and it wasn't obvious to me what
> > went wrong.
>
> It's been discussed here before, both wrt 2.5 and 2.4 with the block
> highmem patches.
>
> > So now I guess I need to either (a) compute the address for the USB layer,
> > or (b) figure out how to pass the memory parameters directly, so we can use
> > highmem.
>
> If you don't set highmem_io in the scsi host structure, then you can
> always do
>
> vaddr = page_address(sg->page) + sg->offset;
>
> --
> Jens Axboe
>
>
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--
Matthew Dharm Home: mdharm-usb@one-eyed-alien.net
Maintainer, Linux USB Mass Storage Driver

My mother not mind to die for stoppink Windows NT! She is rememberink
Stalin!
-- Pitr
User Friendly, 9/6/1998

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