booting without initrd

booting without initrd

[Ram Gupta]

I am trying to boot with 2.6.16  kernel at my desktop running fedora
core 4 . It does not boot without initrd generating the message "VFS:
can not open device "804" or unknown-block(8,4)
Please append a correct "root=" boot option
Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)

I have disabled the module support & built in all modules/drivers for
ide/scsi/sata but it does not boot. I have to disable the module as I
need a statically built  kernel.

If someone could describe the way to boot without initrd it will be great.

Thanks in advance for your cooperation.
Ram Gupta

Re: booting without initrd

[Jan Engelhardt]

> I am trying to boot with 2.6.16  kernel at my desktop running fedora
> core 4 . It does not boot without initrd generating the message "VFS:
> can not open device "804" or unknown-block(8,4)
> Please append a correct "root=" boot option
> Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)
>
> I have disabled the module support & built in all modules/drivers for
> ide/scsi/sata but it does not boot. I have to disable the module as I
> need a statically built  kernel.
>
Recently added patches that show you all filesystems should help 
identifying the cause. Maybe you still have something missing and the 
printk_all_partitions() patch could be helpful.

> If someone could describe the way to boot without initrd it will be great.


Jan Engelhardt
-- 

Re: booting without initrd

[Rahul Karnik]

On 6/7/06, Ram Gupta <ram.gupta5@gmail.com> wrote:
> I am trying to boot with 2.6.16  kernel at my desktop running fedora
> core 4 . It does not boot without initrd generating the message "VFS:
> can not open device "804" or unknown-block(8,4)
> Please append a correct "root=" boot option
> Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)

AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
grub.conf and therefore needs the initrd in order to work correctly.
If you do not want an initrd, then change this to
"root=/dev/<your_disk>" in grub.conf. Note that the reason Fedora uses
the LABEL is so you can move disks around in your system without a
problem, so you should be careful doing so after making the change.

-Rahul
-- 
Rahul Karnik
rahul@genebrew.com

Re: booting without initrd

[Mark Lord]

Rahul Karnik wrote:
>
> AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
> grub.conf and therefore needs the initrd in order to work correctly.
> If you do not want an initrd, then change this to
> "root=/dev/<your_disk>" in grub.conf. Note that the reason Fedora uses
> the LABEL is so you can move disks around in your system without a problem

Heh.. except for people like me, who regularly swap disks around
to boot from different distros, in which case the LABEL=/ continuously
causes nothing but grief until I remember to edit it away.

Cheers

Re: booting without initrd

[David Lang]

On Thu, 8 Jun 2006, Mark Lord wrote:

> Rahul Karnik wrote:
>> 
>> AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
>> grub.conf and therefore needs the initrd in order to work correctly.
>> If you do not want an initrd, then change this to
>> "root=/dev/<your_disk>" in grub.conf. Note that the reason Fedora uses
>> the LABEL is so you can move disks around in your system without a problem
>
> Heh.. except for people like me, who regularly swap disks around
> to boot from different distros, in which case the LABEL=/ continuously
> causes nothing but grief until I remember to edit it away.

not to mention the fact that the label checking code only checks the first 
several drives (I don't know how  many, but I know that it won't find a 
label on sdq :-)

David Lang

Re: booting without initrd

[Mark Rustad]

On Jun 8, 2006, at 9:39 AM, Mark Lord wrote:

> Rahul Karnik wrote:
>>
>> AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
>> grub.conf and therefore needs the initrd in order to work correctly.
>> If you do not want an initrd, then change this to
>> "root=/dev/<your_disk>" in grub.conf. Note that the reason Fedora  
>> uses
>> the LABEL is so you can move disks around in your system without a  
>> problem
>
> Heh.. except for people like me, who regularly swap disks around
> to boot from different distros, in which case the LABEL=/ continuously
> causes nothing but grief until I remember to edit it away.

You would like labels a lot better if you took charge and forced the  
labels to be something like "FC4-root", "SLES9-root" etc. rather than  
the default "/".

-- 
Mark Rustad, MRustad@mac.com

Re: booting without initrd

[Måns Rullgård]

Mark Lord <lkml@rtr.ca> writes:

> Rahul Karnik wrote:
>>
>> AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
>> grub.conf and therefore needs the initrd in order to work correctly.
>> If you do not want an initrd, then change this to
>> "root=/dev/<your_disk>" in grub.conf. Note that the reason Fedora uses
>> the LABEL is so you can move disks around in your system without a problem
>
> Heh.. except for people like me, who regularly swap disks around
> to boot from different distros, in which case the LABEL=/ continuously
> causes nothing but grief until I remember to edit it away.

Yes, there's an old saying that "grief comes with a red hat".

-- 
Måns Rullgård
mru@inprovide.com

Re: booting without initrd

[Arjan van de Ven]

On Thu, 2006-06-08 at 13:40 -0400, Rahul Karnik wrote:
> On 6/7/06, Ram Gupta <ram.gupta5@gmail.com> wrote:
> > I am trying to boot with 2.6.16  kernel at my desktop running fedora
> > core 4 . It does not boot without initrd generating the message "VFS:
> > can not open device "804" or unknown-block(8,4)
> > Please append a correct "root=" boot option
> > Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)
> 
> AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
> grub.conf and therefore needs the initrd in order to work correctly.
> If you do not want an initrd, then change this to
> "root=/dev/<your_disk>" in grub.conf. 

it's more than that; also udev is used from the initrd to populate a
ramfs /dev, if you go without the initrd you need to populate the
*real* /dev manually first

Re: booting without initrd

[Paul Dickson]

On Fri, 09 Jun 2006 02:40:59 +0200, Arjan van de Ven wrote:

> On Thu, 2006-06-08 at 13:40 -0400, Rahul Karnik wrote:
> > On 6/7/06, Ram Gupta <ram.gupta5@gmail.com> wrote:
> > > I am trying to boot with 2.6.16  kernel at my desktop running fedora
> > > core 4 . It does not boot without initrd generating the message "VFS:
> > > can not open device "804" or unknown-block(8,4)
> > > Please append a correct "root=" boot option
> > > Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)
> > 
> > AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
> > grub.conf and therefore needs the initrd in order to work correctly.
> > If you do not want an initrd, then change this to
> > "root=/dev/<your_disk>" in grub.conf. 
> 
> it's more than that; also udev is used from the initrd to populate a
> ramfs /dev, if you go without the initrd you need to populate the
> *real* /dev manually first

Looking through my rc.sysinit (pre-fc6), udev gets started after root is
mounted (I haven't looked at the initrd).

More than likely, something isn't compiled into the kernel (either left
as a module or left out entirely) that is required to access the root
volume.  Without the initrd, no modules can be loaded nor lvm started to
find the root volume.

Where is your root volume and which filesystem are you using.

	-Paul

Re: booting without initrd

[Joe Korty]

On Thu, Jun 08, 2006 at 06:43:25PM -0700, Paul Dickson wrote:
> On Fri, 09 Jun 2006 02:40:59 +0200, Arjan van de Ven wrote:
> > On Thu, 2006-06-08 at 13:40 -0400, Rahul Karnik wrote:
> > > On 6/7/06, Ram Gupta <ram.gupta5@gmail.com> wrote:
> > > > I am trying to boot with 2.6.16  kernel at my desktop running fedora
> > > > core 4 . It does not boot without initrd generating the message "VFS:
> > > > can not open device "804" or unknown-block(8,4)
> > > > Please append a correct "root=" boot option
> > > > Kernel panic - not syncing : VFS:Unable to mount root fs on unknown-block(8,4)
> > > 
> > > AFAIK Fedora sets up the kernel command line with "root=LABEL=/" in
> > > grub.conf and therefore needs the initrd in order to work correctly.
> > > If you do not want an initrd, then change this to
> > > "root=/dev/<your_disk>" in grub.conf. 
> > 
> > it's more than that; also udev is used from the initrd to populate a
> > ramfs /dev, if you go without the initrd you need to populate the
> > *real* /dev manually first

When I do the following to FC5, I am able to boot kernel.org kernels w/o
an initrd:

        # mount --bind / /mnt
	# cd /mnt/dev
	# mknod null c 1 3
	# mknod console c 5 1
	# for i in $(seq 0 9); do mknod tty$i c 4 $i; done
	# cd /
	# umount /mnt

IMHO, FC5's failure to set up a minimal disk-based /dev like this
is a bug on its part.

Regards,
Joe

Re: booting without initrd

[Yaroslav Klyukin]

Ram Gupta wrote:
> I am trying to boot with 2.6.16  kernel at my desktop running fedora
> core 4 . It does not boot without initrd generating the message "VFS:
> can not open device "804" or unknown-block(8,4)
> Please append a correct "root=" boot option
> Kernel panic - not syncing : VFS:Unable to mount root fs on
> unknown-block(8,4)
> 
> I have disabled the module support & built in all modules/drivers for
> ide/scsi/sata but it does not boot. I have to disable the module as I
> need a statically built  kernel.

Depending on the type of SATA you use, the hard disk may be called either /dev/sda or /dev/hda
libata emulates SCSI, so it will be called /dev/sda

Find out which partition is /
Eg: /dev/sda2

Then append root=/dev/sda2 to the kernel boot prompt.
If you are using grub, press "e" for "edit".

All that will work given that you have built the proper IDE or SCSI drivers into the kernel.
Also, make sure you have built the proper filesystem support into the kernel too.

> 
> If someone could describe the way to boot without initrd it will be great.
> 
> Thanks in advance for your cooperation.
> Ram Gupta
> -
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