[9fans] usbd and boot

[Tim Newsham]

How does usbd interact with the boot process? I noticed
that #u gets mounted on /dev and usbd gets run by the boot
process. I don't see /srv/usb getting mounted on /dev (thats
where the devices appear, right?).

If I plug in a usb keyboard during boot, would I get to use
it? If so, how does it get accessed? If I plug in a usb
disk, can I use it as the root filesystem? If so, what kind
of root spec would I need to use?

Tim Newsham | www.thenewsh.com/~newsham | thenewsh.blogspot.com

[erik quanstrom]

> If I plug in a usb keyboard during boot, would I get to use
> it? If so, how does it get accessed?

yes. you don't need to anything. usdb starts kb which
attaches to kbin.

- erik

[erik quanstrom]

i forgot to mention that low-speed only devices with
intel chipsets tend to lock the machine up hard unless
you disable legacy usb emulation in bios.

- erik

[Francisco J Ballesteros]

I tried this on one machine and it worked.
I'll keep trying to see if that's just that machine which works.

I'd like to get debug output (usbdebug=2) for a machine hang.

[erik quanstrom]

On Thu Nov 12 13:36:19 EST 2009, ne...@lsub.org wrote:
> I tried this on one machine and it worked.
> I'll keep trying to see if that's just that machine which works.
>
> I'd like to get debug output (usbdebug=2) for a machine hang.

last bit of output
uhci 0xc400 setting run to 1
uhci 0xc400 cmd 0x1 sts 0x0
uhci init: cmd 0x1 sts 0x0 sof 0x50 flb 0x5a000 frno 0x0 psc0 psc1 0x80

i added some debugging to determine that one actually finishes
the routine and returns to usbinit in devusb.c. on my screen
i see hub 0, 1, 2, 3, 6 on my screen. there's some stuff that's
scrolled off.

it appears to be hanging on a context switch or in an interrupt.
perhaps even an smi interrupt.

- erik

[Francisco J Ballesteros]

Ok. thanks.
If I find out what's wrong I'll drop you a line a send a patch.