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Old 04-05-2008, 08:53 AM   #1
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help in reboot=bios in kernel


hi all
what will happen or what will be the changes if reboot=bios option given in grub's kernel parameter? Can anyone expalin me?
 
Old 04-05-2008, 10:43 AM   #2
aus9
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thats a very good question and I do not use it myself.

what it means is that if you set it on the kernel line....when you issue a normal reboot command within a booted system....it must go to the normal full cold start reboot...the one that goes to the bios screen.

but AFAIK this may be a kernel parameter that is obsolete....circa 2004.

2) can you open a shell and
Code:
su
grub
and post the grub version please.

3) can you also run
strings /boot/grub/stage2 > strings.txt and check for any mention of reboot
 
Old 04-06-2008, 02:47 AM   #3
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Quote:
Originally Posted by aus9 View Post
2) can you open a shell and
Code:
su
grub
and post the grub version please.
For Fedora core 4
grub version is 0.95

For redhat 8.0
grub version is 0.92

For Puppy Linux 3.01
grub version is 0.97

I have checked with reboot=bios in kernel parameter for all the above, none got the difference from normal reboot.

Quote:
Originally Posted by aus9 View Post
3) can you also run
strings /boot/grub/stage2 > strings.txt and check for any mention of reboot
I can found only in two places where the reboot is present, one is reboot and another is Reboot the system string.
 
Old 04-06-2008, 10:44 AM   #4
aus9
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thanks for that

all but puppy have a version thats close to the current edition.

I had already run strings on my own and did not get a reboot= option so thats why I think its not a grub supported option.

BTW...it does not appear in any recent cheat code aka boot parameter either
 
Old 04-08-2008, 12:38 AM   #5
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In linux2.6.23.12 code base's kernel parameters.txt, reboot option is present.when we do make bzImage, the reboot.c in /arch/*/kerenl/reboot.c is complied and is that reboot.o is copied into /sbin folder as reboot?
 
Old 04-08-2008, 03:23 AM   #6
aus9
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well a strings /sbin/reboot gives
usage: %s [-n] [-w] [-d] [-f] [-h] [-i]%s
-n: don't sync before halting the system
-w: only write a wtmp reboot record and exit.
-d: don't write a wtmp record.
-f: force halt/reboot, don't call shutdown.
-h: put harddisks in standby mode.
-i: shut down all network interfaces.
-p: power down the system (if possible, otherwise halt)

2) I am running a vanilla kernel on mdv

3) but you are right...I was looking at knoppix cheat code not the vanilla boot parameter.

I am still none the wiser...if your reboot does not go thru bios....I will have to do some more checking.

will post back if I have a grub kernel line with a reboot= ? parameter that does not use bios.
 
Old 04-08-2008, 07:48 AM   #7
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Thanks asus!
But when i searched for reboot=bios option in google, with lilo only it is used and more over it is to avoid any hang during reboot because of any hardware bug. whatever may be, we just want to know how it is got differ with normal reboot.Thanks for your assistance.
 
Old 04-08-2008, 09:10 AM   #8
aus9
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ok trying to find a boot parameter not easy but
http://lwn.net/Articles/112763/

looks like it.
 
Old 04-09-2008, 05:28 AM   #9
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I am not able to access the link for the patch which is in
http://lwn.net/Articles/112763/
 
Old 04-09-2008, 07:02 AM   #10
aus9
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yes I did say it was not easy...2004 I was referring only to
reboot-force

reboot-nobios

those 2004 links do not work for me either but I assume you knew they were 64 bit?

according to
http://www.x86-64.org/cvsaccess.html

cvs anon has been disabled so I assume the same as occured to ftp
 
Old 04-09-2008, 07:59 AM   #11
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Thaks for the reply. The reason for searching this is, i want to switch from protected mode real mode to make use of int 19h. I searched in google it can't be done in linux because accessing CR0 register is not allowed by user programs. Anyway when system restarts at one stage it will switch to real mode. I have seen reboot comes with different modes like warm, cold, "BIOS". So i trying with that option without knowing it fully (not able to get the details what is the exact reason for it).
 
Old 04-09-2008, 10:55 AM   #12
aus9
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well I am glad you have told us the reason.

this is out of my area of comfort.

I shall sign off.

this looks it may have promise
http://my.execpc.com/~geezer/johnfine/segments.htm
 
  


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