amd64/173078: Followup to amd64/170677: FreeBSD 9.x does not boot if 2 hard disks are on system

[Harald von Fellenberg]

>Number:         173078
>Category:       amd64
>Synopsis:       Followup to amd64/170677: FreeBSD 9.x does not boot if 2 hard disks are on system
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Oct 25 17:40:00 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Harald von Fellenberg
>Release:        FreeBSD 9.1-RC1
>Organization:
>Environment:
FreeBSD orion-freebsd91.von-fellenberg.ch 9.1-RC1 FreeBSD 9.1-RC1 #0: Tue Aug 14 04:25:06 UTC 2012     root at farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64

>Description:
Followup to my earlies bug report  amd64/170677.
I instrumented the loader code (in /usr/src/sys/boot) with various printf's to see where the delay occurs. Here are my findings:

1. in /usr/src/sys/boot/common/devopen.c around line 47:

    /* point to device-specific data so that device open can use it */
    f->f_devdata = dev;
    result = dev->d_dev->dv_open(f, dev);
    if (result != 0) {

the call to dev->d_dev->dv_open(f, dev) always blocks for around 15 seconds, both for existing and non-existing files. Why is that?

2. the loader opens about 19 existing files (among them the kernel at /boot/kernel/kernel five times!) and tries to open about 18 non-existing files (among them /boot/kernel/linker.hints twice). Each open adds about 15 seconds, so the complete time to get to the loader menu is around 10 to 11 minutes.

I do not know why this delay occurs, why it only occurs when 2 HDs are present, and how it can be avoided. every help to solve this riddle is appreciated!
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: