Re: CAM breaks USB [was Re: USB causing boot to hang]

On Fri, Dec 06, 2019 at 03:33:09PM -0700, Warner Losh wrote:
> On Fri, Dec 6, 2019 at 3:31 PM Steve Kargl <sgk_at_troutmask.apl.washington.edu>
> wrote:
> 
> > On Fri, Dec 06, 2019 at 12:23:16PM -0800, Steve Kargl wrote:
> > > I updates /usr/src to r355452, and updated by kernel and
> > > world.  Upon rebooting, verbose boot messages susgests
> > > the system is hanging when USB starts to attach.  With
> > > the 3-week kernel verbose boot shows:
> > >
> > > ...
> > > pcm4: Playback channel matrix is: 2.0 (unknown)
> > > usbus0: 5.0Gbps Super Speed USB v3.0
> > > ...
> > >
> > > end with a prompt on the console.  With today's kernel,
> > > boot is hung after the last pcm4: message and no usbus0
> > > is displayed.
> > >
> > > The booting kernel/system is a
> > >
> > > % uname -a
> > > FreeBSD 13.0-CURRENT #1 r354658: Wed Nov 13 11:23:32 PST 2019,  amd64
> > >
> > > Again, the failing kernel is r 355452
> > >
> >
> > The problem seems to be caused 355010.  This is a commit to
> > fix CAM, which seems to break USB.
> >
> 
> Yes. mav_at_ made this change...
> 

src/UPDATING seems to be missing an entry about CAM breaking USB.

The commit message for 355010 states:

   Devices appearing on USB bus later may still require setting
   kern.cam.boot_delay, but hopefully those are minority.

There is no statement about "where" kern.cam.boot_delay should be set.
There is no statement about "what"  value(s) kern.cam.boot_delay should be.

For the record add kern.cam.boot_delay to /boot/loader.conf with the
values 0, 1, and "1" did not allow the system to boot.  The system
will not boot with or without

umass0 on uhub1
umass0: <Seagate BUP SL, class 0/0, rev 3.00/1.00, addr 2> on usbus0
umass0:  SCSI over Bulk-Only; quirks = 0x0100
umass0:9:0: Attached to scbus9
da0 at umass-sim0 bus 0 scbus9 target 0 lun 0
da0: <Seagate BUP SL 0304> Fixed Direct Access SPC-4 SCSI device
da0: Serial Number NA7PEG27
da0: 400.000MB/s transfers
da0: 3815447MB (7814037167 512 byte sectors)
da0: quirks=0x2<NO_6_BYTE>

plugged into the port.

-- 
Steve