Date: Wed, 09 Feb 2005 09:20:27 -0600 From: Billy Newsom <smartweb@leadhill.net> To: freebsd-hackers@freebsd.org Subject: Cold Reboot (or cold restart) FreeBSD? locore.s hack attempt Message-ID: <420A2A3B.2060507@leadhill.net>
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I want to do a cold reboot of FreeBSD due to (what seens to be) a
problem with the FreeBSD 5.3 system on my particular machine. To make a
long story short, I have determined that FreeBSD 5.3 sputters and coughs
when it tries to reboot this system. (The problem wasn't on 4.7, for
example, and DOS can reboot the machine fine.)
I believe the solution (barring a change of the kernel I'm not sure how
to do) is to merely rewrite the code which send the command to reboot
the system. I want to be able to do a shutdown -r now, or merely a
"reboot" from single user mode, etc. and the system restart, do its full
POST, count memory, and run properly.
So here's my unified diff, which did not seem to work:
-----------------Code
--- locore.s Thu Jul 8 17:35:34 2004
+++ /usr/src/sys/i386/i386/locore.s Wed Feb 2 01:50:36 2005
@@ -214,7 +214,8 @@
movsb
#else /* IBM-PC */
/* Tell the bios to warmboot next time */
- movw $0x1234,0x472
+/* movw $0x1234,0x472 */
+ movw $0x0000,0x472 /* Billy: Perform Cold Reboot! */
#endif /* PC98 */
/* Set up a real frame in case the double return in newboot is
executed. */
-----------------Code
Recompiling my kernel and using that diff did not work. The system
would still lock up and freeze when I attempted to do a shutdown -r now.
The 0x472h address is supposed to point to a region of memory that the
BIOS looks at when deciding to do a cold or warm restart. Perhaps doing
this in locore.s is not working somehow, or that region of memory gets
corrupted.
So to see the full discussion of my problem in detail, see the archives
of the freebsd-questions list:
http://lists.freebsd.org/pipermail/freebsd-questions/2005-January/074567.html
(my original post)
Here's what I came up with:
http://lists.freebsd.org/pipermail/freebsd-questions/2005-February/074728.html
Well, so far I tried this hack:
http://lists.freebsd.org/pipermail/freebsd-questions/2005-February/074867.html
This problem is very weird, because only FreeBSD 5.3 seems to break the
rebooting ability of this machine. The underlying problem might have to
do with some sort of aggressive use of the BIOS memroy region or some
reserved memory which causes a warm (or perhaps even the cold) reboot to
fail. IF that's the case, is there a hack to reserve memory from
FreeBSD's kernel so that these secret regions get left in tact?
Other than that, would someone like to see if my hack of locore.s Works
For Them? I'm curious to see if someone else's computer will perform
the cold restart (count memory). This code region is apparently about
10 years old or more (pre-3.0.5), so it would be interesting to hack it
now. As a side note, I believe that linux and others allow you to
decide on which reboot flavor you prefer.
Thanks,
Billy
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