Re: Initrd or Cdrom as root

Re: Initrd or Cdrom as root

[Tigran Aivazian]

did you forget to pass "rootcd=1" in the boot command line?

When the kernel boots it shows the command line like this:

  Kernel command line: BOOT_IMAGE=linux-nopae ro root=305 BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1

What does it look like in your case?

On Tue, 14 May 2002, Dead2 wrote:

> I tested the patch, but it still does not work..
>
> These are the error messages I get:
> (lines 1,2,3,6 and 7 are prolly not relevant)
>
> ---
> SCSI subsystem driver Revision: 1.00
> 3ware Storage Controller device driver for Linux v1.02.00.016.
> 3w-xxxx: No cards with valid units found.
> request_module[scsi_hostadapter]: Root fs not mounted
> request_module[scsi_hostadapter]: Root fs not mounted
> pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> VFS: Cannot open root device "" or 48:03
> Please append a correct "root=" boot option
> Kernel panic: VFS: Unable to mount root fs on 48:03
> ---
>
> I have compiled in a lot of scsi drivers that are not used, so
> the kernel will be able to boot on just about any system.
> The cdrom on the test computer is on /dev/hdc. But I have
> also tested it on several other computers with no luck.
>
> Attached: My kernel .config
>
> -=Dead2=-
>

Re: Initrd or Cdrom as root

[Dead2]

Unfortunately it boots too fast for me to see that message..

This is my isolinux.cfg file:
---
DEFAULT zoac

LABEL zoac
    KERNEL /boot/bzImage
    APPEND "enableapic rootcd=1"
---
>From what I know, that should work.. right?

-=Dead2=-

----- Original Message -----
From: "Tigran Aivazian" <tigran@veritas.com>
To: "Dead2" <dead2@circlestorm.org>
Cc: <linux-kernel@vger.kernel.org>
Sent: Tuesday, May 14, 2002 7:41 PM
Subject: Re: Initrd or Cdrom as root


> did you forget to pass "rootcd=1" in the boot command line?
>
> When the kernel boots it shows the command line like this:
>
>   Kernel command line: BOOT_IMAGE=linux-nopae ro root=305
BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1
>
> What does it look like in your case?
>
> On Tue, 14 May 2002, Dead2 wrote:
>
> > I tested the patch, but it still does not work..
> >
> > These are the error messages I get:
> > (lines 1,2,3,6 and 7 are prolly not relevant)
> >
> > ---
> > SCSI subsystem driver Revision: 1.00
> > 3ware Storage Controller device driver for Linux v1.02.00.016.
> > 3w-xxxx: No cards with valid units found.
> > request_module[scsi_hostadapter]: Root fs not mounted
> > request_module[scsi_hostadapter]: Root fs not mounted
> > pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> > cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> > VFS: Cannot open root device "" or 48:03
> > Please append a correct "root=" boot option
> > Kernel panic: VFS: Unable to mount root fs on 48:03
> > ---
> >
> > I have compiled in a lot of scsi drivers that are not used, so
> > the kernel will be able to boot on just about any system.
> > The cdrom on the test computer is on /dev/hdc. But I have
> > also tested it on several other computers with no luck.
> >
> > Attached: My kernel .config
> >
> > -=Dead2=-
> >
>
>

Re: Initrd or Cdrom as root

[Tigran Aivazian]

also, don't forget to pass "rootfstype=iso9660" if your cdrom's filesystem
is iso9660. It shouldn't be needed because the kernel tries to mount using
all registered filesystem types in turn, but specifying rootfstype
explicitly avoids silly messages from FAT about wrong sector size so I
always pass it.

On Tue, 14 May 2002, Tigran Aivazian wrote:

> did you forget to pass "rootcd=1" in the boot command line?
>
> When the kernel boots it shows the command line like this:
>
>   Kernel command line: BOOT_IMAGE=linux-nopae ro root=305 BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1
>
> What does it look like in your case?
>
> On Tue, 14 May 2002, Dead2 wrote:
>
> > I tested the patch, but it still does not work..
> >
> > These are the error messages I get:
> > (lines 1,2,3,6 and 7 are prolly not relevant)
> >
> > ---
> > SCSI subsystem driver Revision: 1.00
> > 3ware Storage Controller device driver for Linux v1.02.00.016.
> > 3w-xxxx: No cards with valid units found.
> > request_module[scsi_hostadapter]: Root fs not mounted
> > request_module[scsi_hostadapter]: Root fs not mounted
> > pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> > cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> > VFS: Cannot open root device "" or 48:03
> > Please append a correct "root=" boot option
> > Kernel panic: VFS: Unable to mount root fs on 48:03
> > ---
> >
> > I have compiled in a lot of scsi drivers that are not used, so
> > the kernel will be able to boot on just about any system.
> > The cdrom on the test computer is on /dev/hdc. But I have
> > also tested it on several other computers with no luck.
> >
> > Attached: My kernel .config
> >
> > -=Dead2=-
> >
>
>

Re: Initrd or Cdrom as root

[Tigran Aivazian]

ok, what's your CD-ROM attached to?
is it an IDE or a SCSI CD-ROM?
If scsi, which HBA is it connected to?
And have you compiled kernel support for that HBA?

The major=0x48 is really 72 which is some exotic hardware called
"Compaq Intelligent Drive Array". Do you have an instance of such hardware
in your machine?

And why are you passing "enableapic" boot parameter if it doesn't exist?
(unless it is some new 2.5.x thing)

I assume you are booting Linux 2.4.18, because that is what the patch was
supposed to apply to.

On Tue, 14 May 2002, Dead2 wrote:

> Unfortunately it boots too fast for me to see that message..
>
> This is my isolinux.cfg file:
> ---
> DEFAULT zoac
>
> LABEL zoac
>     KERNEL /boot/bzImage
>     APPEND "enableapic rootcd=1"
> ---
> >From what I know, that should work.. right?
>
> -=Dead2=-
>
> ----- Original Message -----
> From: "Tigran Aivazian" <tigran@veritas.com>
> To: "Dead2" <dead2@circlestorm.org>
> Cc: <linux-kernel@vger.kernel.org>
> Sent: Tuesday, May 14, 2002 7:41 PM
> Subject: Re: Initrd or Cdrom as root
>
>
> > did you forget to pass "rootcd=1" in the boot command line?
> >
> > When the kernel boots it shows the command line like this:
> >
> >   Kernel command line: BOOT_IMAGE=linux-nopae ro root=305
> BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1
> >
> > What does it look like in your case?
> >
> > On Tue, 14 May 2002, Dead2 wrote:
> >
> > > I tested the patch, but it still does not work..
> > >
> > > These are the error messages I get:
> > > (lines 1,2,3,6 and 7 are prolly not relevant)
> > >
> > > ---
> > > SCSI subsystem driver Revision: 1.00
> > > 3ware Storage Controller device driver for Linux v1.02.00.016.
> > > 3w-xxxx: No cards with valid units found.
> > > request_module[scsi_hostadapter]: Root fs not mounted
> > > request_module[scsi_hostadapter]: Root fs not mounted
> > > pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> > > cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> > > VFS: Cannot open root device "" or 48:03
> > > Please append a correct "root=" boot option
> > > Kernel panic: VFS: Unable to mount root fs on 48:03
> > > ---
> > >
> > > I have compiled in a lot of scsi drivers that are not used, so
> > > the kernel will be able to boot on just about any system.
> > > The cdrom on the test computer is on /dev/hdc. But I have
> > > also tested it on several other computers with no luck.
> > >
> > > Attached: My kernel .config
> > >
> > > -=Dead2=-
> > >
> >
> >
>
>

Re: Initrd or Cdrom as root

[William Stearns]

Good day, Mr. Expired,

On Tue, 14 May 2002, Dead2 wrote:

> Unfortunately it boots too fast for me to see that message..

dmesg | less
less /var/log/dmesg
	Some distributions save the boot time dmesg output here.
	Cheers,
	- Bill

---------------------------------------------------------------------------
        "Of course my password is the same as my pet's name.  My dog's
name was Q47pY!3$H9x, but I change it every 90 days."
        -- Ken Pfeil <kpfeil@MIRADIANT.COM>
--------------------------------------------------------------------------
William Stearns (wstearns@pobox.com).  Mason, Buildkernel, named2hosts, 
and ipfwadm2ipchains are at:                        http://www.stearns.org
--------------------------------------------------------------------------

Re: Initrd or Cdrom as root

[Dead2]

The computer is an Compaq Proliant DL360 1U-Rack server
The cdrom is connected to an IDE controller as /dev/hdc

Yes it has a Compaq SMART2 Raid controller, but both drives
have been disconnected so that they don't interfere with booting.
(If connected, it loads kernel from cdrom, then loads root from HDD)

This CDROM is supposed to be able to be inserted into a fresh
server with no partitions on the HDD's. When booted, it will detect
the HDD, partition it and then install some rpm packages to get a
basic setup running.

I have also tested this cdrom in a few other computers with the
same error messages.

"enableapic"? I just assumed it existed.

----- Original Message -----
From: "Tigran Aivazian" <tigran@veritas.com>


> ok, what's your CD-ROM attached to?
> is it an IDE or a SCSI CD-ROM?
> If scsi, which HBA is it connected to?
> And have you compiled kernel support for that HBA?
>
> The major=0x48 is really 72 which is some exotic hardware called
> "Compaq Intelligent Drive Array". Do you have an instance of such hardware
> in your machine?
>
> And why are you passing "enableapic" boot parameter if it doesn't exist?
> (unless it is some new 2.5.x thing)
>
> I assume you are booting Linux 2.4.18, because that is what the patch was
> supposed to apply to.
>
> On Tue, 14 May 2002, Dead2 wrote:
>
> > Unfortunately it boots too fast for me to see that message..
> >
> > This is my isolinux.cfg file:
> > ---
> > DEFAULT zoac
> >
> > LABEL zoac
> >     KERNEL /boot/bzImage
> >     APPEND "enableapic rootcd=1"
> > ---
> > >From what I know, that should work.. right?
> >
> > -=Dead2=-
> >
> > ----- Original Message -----
> > From: "Tigran Aivazian" <tigran@veritas.com>
> > To: "Dead2" <dead2@circlestorm.org>
> > Cc: <linux-kernel@vger.kernel.org>
> > Sent: Tuesday, May 14, 2002 7:41 PM
> > Subject: Re: Initrd or Cdrom as root
> >
> >
> > > did you forget to pass "rootcd=1" in the boot command line?
> > >
> > > When the kernel boots it shows the command line like this:
> > >
> > >   Kernel command line: BOOT_IMAGE=linux-nopae ro root=305
> > BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1
> > >
> > > What does it look like in your case?
> > >
> > > On Tue, 14 May 2002, Dead2 wrote:
> > >
> > > > I tested the patch, but it still does not work..
> > > >
> > > > These are the error messages I get:
> > > > (lines 1,2,3,6 and 7 are prolly not relevant)
> > > >
> > > > ---
> > > > SCSI subsystem driver Revision: 1.00
> > > > 3ware Storage Controller device driver for Linux v1.02.00.016.
> > > > 3w-xxxx: No cards with valid units found.
> > > > request_module[scsi_hostadapter]: Root fs not mounted
> > > > request_module[scsi_hostadapter]: Root fs not mounted
> > > > pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> > > > cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> > > > VFS: Cannot open root device "" or 48:03
> > > > Please append a correct "root=" boot option
> > > > Kernel panic: VFS: Unable to mount root fs on 48:03
> > > > ---
> > > >
> > > > I have compiled in a lot of scsi drivers that are not used, so
> > > > the kernel will be able to boot on just about any system.
> > > > The cdrom on the test computer is on /dev/hdc. But I have
> > > > also tested it on several other computers with no luck.
> > > >
> > > > Attached: My kernel .config
> > > >
> > > > -=Dead2=-
> > > >
> > >
> > >
> >
> >
>
>

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Tue, 14 May 2002, William Stearns wrote:

> Good day, Mr. Expired,
>
> On Tue, 14 May 2002, Dead2 wrote:
>
> > Unfortunately it boots too fast for me to see that message..
>
> dmesg | less
> less /var/log/dmesg
> 	Some distributions save the boot time dmesg output here.
> 	Cheers,
> 	- Bill

And how exactly do you suggest to type that command if the kernel panics?
If he had kdb he could do "mds saved_command_line 100".

I suspect that whatever is he using for creating the images (what is this
"isolinux.cfg"?) has modified the boot command line and that is why it
fails. It works fine for me (and worked since the time I wrote it around
2.4.0 or so).

Regards
Tigran

Re: Initrd or Cdrom as root

[Dead2]

> I suspect that whatever is he using for creating the images (what is this
> "isolinux.cfg"?) has modified the boot command line and that is why it
> fails. It works fine for me (and worked since the time I wrote it around
> 2.4.0 or so).

Isolinux: http://syslinux.zytor.com/iso.php

If you have a tutorial of how to make a bootable cdrom that does not use
Isolinux, then please point me to it.. =)

To make the iso image I use the following command:

'mkisofs -b isolinux.bin -o test.iso -no-emul-boot -boot-load-size
4 -boot-info-table /iso'

-=Dead2=-

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Tue, 14 May 2002, Dead2 wrote:
> This CDROM is supposed to be able to be inserted into a fresh
> server with no partitions on the HDD's. When booted, it will detect
> the HDD, partition it and then install some rpm packages to get a
> basic setup running.

Hmmm, that is called a Linux distribution btw :)

> I have also tested this cdrom in a few other computers with the
> same error messages.
>
> "enableapic"? I just assumed it existed.

perhaps it _should_ exist to enable the user the override a hardcoded
"noapic" option in the image. I.e. you may build a floppy/cd with "noapic"
hardcoded in lilo.conf but it is convenient to be able to override it.
When I added "noapic" option this didn't occur to me... Or, perhaps a
better syntax is "ioapics=0" and "ioapics=1" but this gives an impression
that one can also say "ioapics=2" which is not the same as the easy
solution above.

Regards
Tigran

>
> ----- Original Message -----
> From: "Tigran Aivazian" <tigran@veritas.com>
>
>
> > ok, what's your CD-ROM attached to?
> > is it an IDE or a SCSI CD-ROM?
> > If scsi, which HBA is it connected to?
> > And have you compiled kernel support for that HBA?
> >
> > The major=0x48 is really 72 which is some exotic hardware called
> > "Compaq Intelligent Drive Array". Do you have an instance of such hardware
> > in your machine?
> >
> > And why are you passing "enableapic" boot parameter if it doesn't exist?
> > (unless it is some new 2.5.x thing)
> >
> > I assume you are booting Linux 2.4.18, because that is what the patch was
> > supposed to apply to.
> >
> > On Tue, 14 May 2002, Dead2 wrote:
> >
> > > Unfortunately it boots too fast for me to see that message..
> > >
> > > This is my isolinux.cfg file:
> > > ---
> > > DEFAULT zoac
> > >
> > > LABEL zoac
> > >     KERNEL /boot/bzImage
> > >     APPEND "enableapic rootcd=1"
> > > ---
> > > >From what I know, that should work.. right?
> > >
> > > -=Dead2=-
> > >
> > > ----- Original Message -----
> > > From: "Tigran Aivazian" <tigran@veritas.com>
> > > To: "Dead2" <dead2@circlestorm.org>
> > > Cc: <linux-kernel@vger.kernel.org>
> > > Sent: Tuesday, May 14, 2002 7:41 PM
> > > Subject: Re: Initrd or Cdrom as root
> > >
> > >
> > > > did you forget to pass "rootcd=1" in the boot command line?
> > > >
> > > > When the kernel boots it shows the command line like this:
> > > >
> > > >   Kernel command line: BOOT_IMAGE=linux-nopae ro root=305
> > > BOOT_FILE=/boot/vmlinuz-2.4.18 rootcd=1
> > > >
> > > > What does it look like in your case?
> > > >
> > > > On Tue, 14 May 2002, Dead2 wrote:
> > > >
> > > > > I tested the patch, but it still does not work..
> > > > >
> > > > > These are the error messages I get:
> > > > > (lines 1,2,3,6 and 7 are prolly not relevant)
> > > > >
> > > > > ---
> > > > > SCSI subsystem driver Revision: 1.00
> > > > > 3ware Storage Controller device driver for Linux v1.02.00.016.
> > > > > 3w-xxxx: No cards with valid units found.
> > > > > request_module[scsi_hostadapter]: Root fs not mounted
> > > > > request_module[scsi_hostadapter]: Root fs not mounted
> > > > > pci_hotplug: PCI Hot Plug PCI Core version: 0.3
> > > > > cpqphp.o: Compaq Hot Plug PCI Controller Driver version 0.9.6
> > > > > VFS: Cannot open root device "" or 48:03
> > > > > Please append a correct "root=" boot option
> > > > > Kernel panic: VFS: Unable to mount root fs on 48:03
> > > > > ---
> > > > >
> > > > > I have compiled in a lot of scsi drivers that are not used, so
> > > > > the kernel will be able to boot on just about any system.
> > > > > The cdrom on the test computer is on /dev/hdc. But I have
> > > > > also tested it on several other computers with no luck.
> > > > >
> > > > > Attached: My kernel .config
> > > > >
> > > > > -=Dead2=-
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Tue, 14 May 2002, Dead2 wrote:
> Isolinux: http://syslinux.zytor.com/iso.php
>
> If you have a tutorial of how to make a bootable cdrom that does not use
> Isolinux, then please point me to it.. =)

I don't have a tutorial, unfortunately. I just wrote the necessary scripts
myself. Besides, this is not something fundamental where one should rely
on the work of others, imho. Creating a bootable CD is too "custom" to be
generic and when it is made generic you end up with problems like you are
having, i.e. not knowing exactly what is going on.

But the basic steps I do are:

a) generate the 2.88M floppy image on /dev/ram0 and fake the geometry like
this:

disk=/dev/ram0
  bios=0
  sectors=36 # or 18 for 1.44M
  cylinders=80
  heads=2

b) make the minimum content of the image:

mkdir boot dev etc
mknod dev/null c 1 3
mknod dev/ram1 b 1 1
mknod dev/zero c 1 5

c) copy the kernel image and LILO bits in there

d) lilo -r /mnt ; umount /mnt

e) dd if=/dev/ram0 of=boot/boot2880.img bs=1k count=2880

f) mkisofs -b boot/boot2880.img -c boot/boot.cat \
        -J -R -quiet \
        -o image.iso

(actually, I add a lot more parameters to mkisofs but they are too
specific to my task so are not interesting)


>
> To make the iso image I use the following command:
>
> 'mkisofs -b isolinux.bin -o test.iso -no-emul-boot -boot-load-size
> 4 -boot-info-table /iso'
>

Interesting, so you are saying that the modern BIOSes are already capable
of booting no-emulation CDs? Last time I tried it (perhaps a year ago)
some of my Dell machines couldn't do it so I gave up and decided to live
with the 2.88M limit. I thought that BIOSes only support enough of "no
emulation" to boot Windows installation CD.

But if things changed and I should revisit the idea (i.e. if it is now
possible to have boot images larger than 2.88M in a portable manner) then
I would like to know.

Regards
Tigran

Re: Initrd or Cdrom as root

[Dead2]

> I suspect that whatever is he using for creating the images (what is this
> "isolinux.cfg"?) has modified the boot command line and that is why it
> fails. It works fine for me (and worked since the time I wrote it around
> 2.4.0 or so).

Your assumption is correct!

It seems that isolinux does not pass the append parameters at all.
The booting works fine when I made your patch use cdrom as root
no matter what.

> This is my isolinux.cfg file:
> ---
> DEFAULT zoac
>
> LABEL zoac
>     KERNEL /boot/bzImage
>     APPEND "enableapic rootcd=1"
> ---

-=Dead2=-

Re: Initrd or Cdrom as root

[Dead2]

> Interesting, so you are saying that the modern BIOSes are already capable
> of booting no-emulation CDs? Last time I tried it (perhaps a year ago)
> some of my Dell machines couldn't do it so I gave up and decided to live
> with the 2.88M limit.
> But if things changed and I should revisit the idea (i.e. if it is now
> possible to have boot images larger than 2.88M in a portable manner) then
> I would like to know.

Indeed it seems like it works on most computers here atleast, and I would
like to explore this way of doing it before boiling out of it just to find
new
problems arising with other ways.

So, I now have a new problem I hope someone can help me out with.
It now mounts the cdrom as root like it should, but then gives me the error:
"Warning: unable to open an initial console."

I have checked everything I can think of, but if someone could point me to
exactly generates this error, I would be forever grateful.

-=Dead2=-

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Wed, 15 May 2002, Dead2 wrote:
> So, I now have a new problem I hope someone can help me out with.
> It now mounts the cdrom as root like it should, but then gives me the error:
> "Warning: unable to open an initial console."
>
> I have checked everything I can think of, but if someone could point me to
> exactly generates this error, I would be forever grateful.

Yes, that is well-known.

Unix root filesystem cannot be readonly in its entirety. Linux is much
better, but even Linux is not perfect.

So, what I do is --- I prepare the /var, /home, /etc, /dev in a tar.gz
file and place it on CD. Then, from rc.sysinit I mount tmpfs on those
points and unpack the tar.gz from / --- thus ending up with readwrite /var
/home /etc and /dev. (you could avoid /dev issue by using devfs but then
you will have other little problems to deal with :)

Btw, you will encounter lots of other problems, of course. Making a Linux
distribution is fun (I enjoy it) but it is not as trivial as some think.
It is certainly not a "pile of rpms" and Red Hat certainly do _not_ "just
package some free software" and sell it. Even without going into the level
of producing _general purpose_ distribution (which is what Red Hat Linux
is), making a (even specialized) Linux distribution is non-trivial. But it
is fun, try it :)

Regards
Tigran

Re: Initrd or Cdrom as root

[Justin Cormack]

> 
> On Wed, 15 May 2002, Dead2 wrote:
> > So, I now have a new problem I hope someone can help me out with.
> > It now mounts the cdrom as root like it should, but then gives me the error:
> > "Warning: unable to open an initial console."
> >
> > I have checked everything I can think of, but if someone could point me to
> > exactly generates this error, I would be forever grateful.
> 
> Yes, that is well-known.
> 
> Unix root filesystem cannot be readonly in its entirety. Linux is much
> better, but even Linux is not perfect.
> 
> So, what I do is --- I prepare the /var, /home, /etc, /dev in a tar.gz
> file and place it on CD. Then, from rc.sysinit I mount tmpfs on those
> points and unpack the tar.gz from / --- thus ending up with readwrite /var
> /home /etc and /dev. (you could avoid /dev issue by using devfs but then
> you will have other little problems to deal with :)

no this is not true. I use busybox plus devfs and it works perfecly read
only. Or you can run the entire system out of an initrd which you can
of course write to if you want to write (it makes some things a little
easier). You can always mount /tmp with tmpfs if you want some write space.

Unable to open an initial console sounds to me like dev is not populated.
Have you got /dev/console and /dev/tty0? I do recommend devfs for this
type of thing, as it makes scripting your initial installer easier (you
can loop over /dev/hd* and so on).

Justin

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Wed, 15 May 2002, Justin Cormack wrote:

> >
> > On Wed, 15 May 2002, Dead2 wrote:
> > > So, I now have a new problem I hope someone can help me out with.
> > > It now mounts the cdrom as root like it should, but then gives me the error:
> > > "Warning: unable to open an initial console."
> > >
> > > I have checked everything I can think of, but if someone could point me to
> > > exactly generates this error, I would be forever grateful.
> >
> > Yes, that is well-known.
> >
> > Unix root filesystem cannot be readonly in its entirety. Linux is much
> > better, but even Linux is not perfect.
> >
> > So, what I do is --- I prepare the /var, /home, /etc, /dev in a tar.gz
> > file and place it on CD. Then, from rc.sysinit I mount tmpfs on those
> > points and unpack the tar.gz from / --- thus ending up with readwrite /var
> > /home /etc and /dev. (you could avoid /dev issue by using devfs but then
> > you will have other little problems to deal with :)
>
> no this is not true. I use busybox plus devfs and it works perfecly read
> only. Or you can run the entire system out of an initrd which you can
> of course write to if you want to write (it makes some things a little
> easier). You can always mount /tmp with tmpfs if you want some write space.
>
> Unable to open an initial console sounds to me like dev is not populated.
> Have you got /dev/console and /dev/tty0? I do recommend devfs for this
> type of thing, as it makes scripting your initial installer easier (you
> can loop over /dev/hd* and so on).

if he is scripting a (limited) initial installer then that is fine. What I
was talking about is a complete system which is flexible enough to be run
either from the CD or from HD. So, I don't say the word "installation", I
say "replicating itself onto a stable (and writeable) media, e.g. hard
disk". And the "system configuration" is not a "passive" one (i.e. you
just store info to be applied to the installed system) but an "active" one
(i.e. you immediately configure the running instance and then, possibly
(if desired) replicate that configuration onto the installed system).

And for such system, my statement is correct, i.e. you do need writeable
/var (for daemons to do logging etc), writeable /home (for multiple users
to compile their programs in there), writeable /dev for gettys etc.

I don't know what a "busybox" is, another recent invention?

Regards
Tigran

--------
The progress is a stupid being, because it is always going forward instead
of stopping for a little while to think and to contemplate its own existence.

Re: [syslinux] Re: Initrd or Cdrom as root

[H. Peter Anvin]

Dead2 wrote:
> 
>>This is my isolinux.cfg file:
>>---
>>DEFAULT zoac
>>
>>LABEL zoac
>>    KERNEL /boot/bzImage
>>    APPEND "enableapic rootcd=1"
>>---
> 

Ditch the quotation marks!

	-hpa

Re: Initrd or Cdrom as root

[Tigran Aivazian]

On Tue, 14 May 2002, Hans K. Rosbach wrote:

> Is there any way to dynamically load initrd or cdrom permanently as
> the root fs when booting from cdrom?
>
> My problem is that I need a reliable way to ALWAYS find the correct
> device to mount. Is there any way to make the kernel automagically
> mount the cdrom it booted from?

yes, just pass rootcd=1 as a boot command line option with the hack below
applied. Make sure that cdrom support is always compiled statically,
otherwise it will break.

--- 2418-/drivers/cdrom/cdrom.c	Fri Nov 16 18:14:08 2001
+++ 2418-rootparam/drivers/cdrom/cdrom.c	Tue Mar 12 00:29:54 2002
@@ -2480,6 +2480,11 @@
         return proc_dostring(ctl, write, filp, buffer, lenp);
 }

+kdev_t get_cdrom_dev(void)
+{
+	return topCdromPtr ? topCdromPtr->dev : 0;
+}
+
 /* Unfortunately, per device settings are not implemented through
    procfs/sysctl yet. When they are, this will naturally disappear. For now
    just update all drives. Later this will become the template on which
--- 2418-/init/main.c	Mon Feb 25 19:38:13 2002
+++ 2418-rootparam/init/main.c	Tue Mar 12 00:29:54 2002
@@ -311,6 +311,16 @@

 __setup("root=", root_dev_setup);

+static int rootcd_enable __initdata = 0;
+
+static int __init rootcd_setup(char *str)
+{
+	get_option(&str, &rootcd_enable);
+	return 1;
+}
+
+__setup("rootcd=", rootcd_setup);
+
 static int __init checksetup(char *line)
 {
 	struct kernel_param *p;
@@ -772,6 +782,10 @@
 	rd_load();
 #endif

+	if (rootcd_enable) {
+		extern kdev_t get_cdrom_dev(void);
+		ROOT_DEV = get_cdrom_dev();
+	}
 	/* Mount the root filesystem.. */
 	mount_root();

Initrd or Cdrom as root

[Hans K. Rosbach]

Is there any way to dynamically load initrd or cdrom permanently as
the root fs when booting from cdrom?

My problem is that I need a reliable way to ALWAYS find the correct
device to mount. Is there any way to make the kernel automagically
mount the cdrom it booted from?
I believe that for example SuSE installer cd does this, but I cannot figure
out how they do it.

If on initrd, I need about 300MB space on the root fs.

If this is not possible, what do I need to modify in the kernel?

-HKR