In message: <6e9b5ff6-685b-427c-87a7-c95850da5...@mac.com>
Marcel Moolenaar <xcl...@mac.com> writes:
:
: On Feb 16, 2009, at 4:35 PM, M. Warner Losh wrote:
:
: > In message: <741faa3b-b91a-4a23-b47f-21141a8d0...@mac.com>
: > Marcel Moolenaar <xcl...@mac.com> writes:
: > :
: > : On Feb 16, 2009, at 3:13 PM, M. Warner Losh wrote:
: > :
: > : > In message: <acb7dff1-6c8e-4936-9bd9-bb2fd375f...@mac.com>
: > : > Marcel Moolenaar <xcl...@mac.com> writes:
: > : > : Before I dig into the code, what's the current status of
: > : > : root mounts on USB mass storage devices?
: > : >
: > : > First, there's a kludge-o-round that is similar to your "sleep 10"
: > : > that you've added. It loops waiting for more devices to show up
: > if
: > : > the desired root file system hasn't appeared yet.
: > : >
: > : > There's no way for hot-plug busses to tell the kernel "I've
: > tried my
: > : > best to enumerate everything on my bus, and I'm done"
: > :
: > : Of course there is. Any and all USB hubs have a certain
: > : number of ports. You can trivially iterate over all of
: > : them and declare completion when you've tried them all.
: >
: > The hot-plug busses know. The mountroot code doesn't have a way to
: > wait for the hot-plug busses.
:
: Huh?
: root_mount_hold() and root_mount_rel() are specifically
: designed to inform the mountroot code that it needs to
: wait (or that it should go ahead and mount root).
r145250 | phk | 2005-04-18 15:21:26 -0600 (Mon, 18 Apr 2005) | 12 lines
Add a named reference-count KPI to hold off mounting of the root filesystem.
While we wait for holds to be released, print a list of who holds us
back once per second.
Use the new KPI from GEOM instead of vfs_mount.c calling g_waitidle().
Use the new KPI also from ata.
With ATAmkIII's newbusification, ata could narrowly miss the window
and ad0 would not exist when we tried to mount root.
----
But it looks like the old usb code didn't call it either... I think
old code enumerated right away during boot, while the new code defers
the enumeration until events can be processed...
Warner
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