Messages in this thread | | | Date | Wed, 2 Jan 2002 21:23:35 +0100 | From | Jens Axboe <> | Subject | Re: [linux-usb-devel] Re: highmem and usb [was "sr: unaligned transfer" in 2.5.2-pre1] |
| |
On Wed, Jan 02 2002, David Brownell wrote: > > > OK, I think I'm clear on this much then: in 2.5, to support block drivers > > > over USB (usb-storage only, for now) there needs to be an addition to > > > the buffer addressing model in usbcore, as exposed by URBs. > > > > > > - Current "transfer_buffer" + "transfer_buffer_length" mode needs to > > > stay, since most drivers aren't block drivers. > > > > Why? Surely USB block drivers are not the only ones that want to support > > highmem. > > Once the capability is there, it'll find other uses. But allowing > them is not the same as requiring them. Getting rid of the current > model would break every USB driver, rather than just ones that want to > support highmem.
So? Either you want to fix this now, or leave it that way forever. Just IMO of course, but you might as well just make a clean break.
> > > - Add some kind of "page + offset" addressing model. > > > > Yes > > > > > Discussion of details can be taken off LKML, it'd seem. Though > > > I'm curious when the scatterlist->address field will vanish, > > > making these changes a requirement. Is that a 2.5.2 thing? > > > > Maybe 2.5.3, dunno for sure. > > A bit of a delay would make things a bit easier ... :) Of course, if > scatterlist->address doesn't work any more, it won't matter much.
A bit of delay will only make things worse, afaics.
-- Jens Axboe
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |