Re: Booting from usb hard disk

On Tuesday 24 March 2009, Paul B. Mahol wrote:
> On 3/24/09, Nenhum_de_Nos <matheus_at_eternamente.info> wrote:
> > On Mon, March 23, 2009 20:46, Paul B. Mahol wrote:
> >> On 3/23/09, Robert Noland <rnoland_at_freebsd.org> wrote:
> >>> On Mon, 2009-03-23 at 11:41 -0400, Douglas Berry wrote:
> >>>> On Mon, 23 Mar 2009 05:36:15 CDT, Robert Noland wrote:
> >>>> > So I have my i386 install on a usb hard disk, which I can only boot
> >>>> > on one machine now.  The one machine that I can make work has a bios
> >>>> > option that reads "BIOS ehci handoff".  This used to work with the
> >>>> > old usb stack.  The machines that it doesn't work on, boot the
> >>>> > kernel, but fail to mount root, giving me the forbidding mountroot>
> >>>> > prompt, which is immediately followed by the message saying that da0
> >>>> > is attached.  da0 is however not listed in the available boot
> >>>> > devices list.  I tried playing around with the timeout in
> >>>> > vfs_mount.c, but that didn't seem to have any impact.  It has been
> >>>> > suggested that this may be a "geom" timeout, but I don't know
> >>>> > anything about the boot system really.
> >>>>
> >>>> I have been using tunefs(8) labeled partitions on my usb hard disk
> >>>> under CURRENT. I changed the fstab entries to match the labels
> >>>> (eg. assume mylabel is myroot, /dev/da0s1a becomes /dev/ufs/myroot)
> >>>> It works well on most systems.  On some systems, I see the symptom
> >>>> you show, but I am saved by the labels showing up just after the
> >>>> mountroot prompt.  I am then able to type
> >>>>
> >>>> 	ufs:/dev/ufs/myroot
> >>>>
> >>>> and resume the boot.  Maybe this helps you?
> >>>
> >>> Well, I haven't tried labeling the partitions, but ufs:/dev/da0s1a
> >>> doesn't work from the rootmount> prompt.  Even after da0 shows up.
> >>
> >> That is strange, I just recently have used one of usb sticks (256MB) to
> >> fix
> >> stupid sysinstall error. In my case da0 appeared after some delay but
> >> usual da0s1a appeared after ? and I was able to mount root
> >> partition multiple times.
> >> I used usb via modules, on i386 revision r190297, with "boot -s"
> >> (I hacked fbsd installation on stick because I didnt have time for fine
> >> details ....)
> >>
> >> Could try just with uhci (but it will be too sloow)
> >
> > how can I make it use this module and not another ? (how to force)
>
> I doubt it will help but anyway ...
>
> Just ensure that you are using custom kernel without any of usb, ehci,
> uhci, etc lines. And forcing uhci is simple, just dont kldload ehci
> (or dont "load echi" from boot loader prompt) and load any other usb
> modules you need.

There is also a new sysctl to do this runtime:

sysctl hw.usb2.ehci.no_hs=1

--HPS