On Wednesday 11 January 2017 16:23:29 Alan Stern wrote:
> On Tue, 10 Jan 2017, James Bottomley wrote:
> > On Tue, 2017-01-10 at 16:00 -0500, Alan Stern wrote:
> > > In theory, I suppose we could change the kernel so that it would
> > > default to READ CAPACITY(16) for devices that report a SCSI level
> > > >= 3, or something along those lines. In general we hesitate to
> > > make changes of this sort, because they almost always end up
> > > breaking _some_ devices -- and if that happens then the change
> > > is reverted, with no exceptions. Linus has a very strict rule
> > > about not breaking working systems.
> >
> > You shouldn't have to change anything: it already does (otherwise
> > how else would we detect physical exponent for proper SCSI
> > devices) see sd.c:sd_try_rc16_first(). It always returns false
> > for USB because you set sdev->try_rc_10_first
>
> In fact, this approach probably won't work. See Bugzilla entries
> #43265 and #43391. The devices in those reports claimed to be ANSI
> level 4, but they failed anyway.
Seems those devices return capacity 0x7F000000000001 or 0xFF000000000001
Maybe there is some error pattern?
> If you guys want to try the quirk flag, you can apply the patch
> below. Then set the usb-storage module parameter quirks=vvvv:pppp:k
> where vvvv and pppp are the Vendor and Product ID codes for your
> device (as 4 hex digits).
>
> In the long run, however, this is not a viable approach. We'd be
> better off with an explicit blacklist.
Ok, so what are next steps? I think that explicit blacklist would be
needed if "bad" devices is less.
How many bug reports were there?
> Alan Stern
>
>
>
> Index: usb-4.x/drivers/usb/storage/usb.c
> ===================================================================
> --- usb-4.x.orig/drivers/usb/storage/usb.c
> +++ usb-4.x/drivers/usb/storage/usb.c
> @@ -498,7 +498,7 @@ void usb_stor_adjust_quirks(struct usb_d
> US_FL_INITIAL_READ10 | US_FL_WRITE_CACHE |
> US_FL_NO_ATA_1X | US_FL_NO_REPORT_OPCODES |
> US_FL_MAX_SECTORS_240 | US_FL_NO_REPORT_LUNS |
> - US_FL_ALWAYS_SYNC);
> + US_FL_ALWAYS_SYNC | US_FL_NEEDS_CAP16);
>
> p = quirks;
> while (*p) {
> @@ -551,6 +551,9 @@ void usb_stor_adjust_quirks(struct usb_d
> case 'j':
> f |= US_FL_NO_REPORT_LUNS;
> break;
> + case 'k':
> + f |= US_FL_NEEDS_CAP16;
> + break;
> case 'l':
> f |= US_FL_NOT_LOCKABLE;
> break;
--
Pali Rohár
pali.rohar@xxxxxxxxx
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