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Old 01-05-2011, 10:50 AM
Alex Schuster
 
Default Changing boot device with 2.6.36

Jörg Schaible writes:

> Alex Schuster wrote:

> > I would be surprised if it had this feature. AFAIK grub is already done
> > at this stage, the kernel has taken over. And I guess it does not know
> > about the LABEL= syntax, and has no code to scan all devices for file
> > system labels.
>
> I fear so, too. Grub finds the boot device properly, it's the kernel
> complaining about the value in the root option.
>
> > With an initramfs, the kernel runs an init script which can do various
> > stuff, like probing all devices for file system labels.
>
> I never had the need for an initrd.

Now you do

Wonko
 
Old 01-05-2011, 11:35 AM
Dale
 
Default Changing boot device with 2.6.36

Jörg Schaible wrote:

that approves my tests ... :-/

Had to boot this morning 5 times, since the root device switched arbitrarily
between sde3 and sdg3 and I've chosen by bad luck always the wrong one. It
seems there is also some timing involved regarding the initialization of the
available devices ... sigh.

- Jörg




I had to reboot last night and was in my BIOS looking for other things
but did notice this feature. I have a setting in my BIOS that tells it
what drive to look for to boot first. It's above the part where you
tell it to boot CDROM, hard drive, floppy, ZIP and other bootable
things. You may want to check and see if you have the same thing. Mine
is called "hard disk boot priority". I'm not sure this will help but it
couldn't hurt to check I guess.


I also noticed something else that may not be related. I enabled AHCI a
while back and noticed it will not boot from a CD/DVD when in that
mode. I have to set it back to IDE for it to be able to boot from other
than the hard drive. Maybe if you set yours to AHCI, it will skip the
external stuff like USB?


I'm seriously pulling it out my butt here. I hope one of these will
help. ;-)


Dale

:-) :-)
 
Old 01-05-2011, 04:18 PM
Mark Knecht
 
Default Changing boot device with 2.6.36

On Wed, Jan 5, 2011 at 3:50 AM, Alex Schuster <wonko@wonkology.org> wrote:
> Jörg Schaible writes:
>
>> Alex Schuster wrote:
>
>> > I would be surprised if it had this feature. AFAIK grub is already done
>> > at this stage, the kernel has taken over. And I guess it does not know
>> > about the LABEL= syntax, and has no code to scan all devices for file
>> > system labels.
>>
>> I fear so, too. Grub finds the boot device properly, it's the kernel
>> complaining about the value in the root option.
>>
>> > With an initramfs, the kernel runs an init script which can do various
>> > stuff, like probing all devices for file system labels.
>>
>> I never had the need for an initrd.
>
> Now you do
>
> * * * *Wonko

Wonko,
I did my first initramfs build this last week to get RAID6 working
for /. It went well and I was impressed at how much I could debug in a
shell before I got it working correctly. (Big issue for me - make sure
you copy all the /dev/sdX stuff you are going to need into the
initramfs, and make sure mdadm is built static.)

QUESTION: What's the difference between initrd and initramfs in
practice. As I understand it initramfs is the newer one. I assume that
means it's preferred? Or are there times when someone wants to still
use an initrd?

Thanks,
Mark
 
Old 01-05-2011, 07:09 PM
Alan McKinnon
 
Default Changing boot device with 2.6.36

Apparently, though unproven, at 19:18 on Wednesday 05 January 2011, Mark
Knecht did opine thusly:

> On Wed, Jan 5, 2011 at 3:50 AM, Alex Schuster <wonko@wonkology.org> wrote:
> > Jörg Schaible writes:
> >> Alex Schuster wrote:
> >> > I would be surprised if it had this feature. AFAIK grub is already
> >> > done at this stage, the kernel has taken over. And I guess it does
> >> > not know about the LABEL= syntax, and has no code to scan all devices
> >> > for file system labels.
> >>
> >> I fear so, too. Grub finds the boot device properly, it's the kernel
> >> complaining about the value in the root option.
> >>
> >> > With an initramfs, the kernel runs an init script which can do various
> >> > stuff, like probing all devices for file system labels.
> >>
> >> I never had the need for an initrd.
> >
> > Now you do
> >
> > Wonko
>
> Wonko,
> I did my first initramfs build this last week to get RAID6 working
> for /. It went well and I was impressed at how much I could debug in a
> shell before I got it working correctly. (Big issue for me - make sure
> you copy all the /dev/sdX stuff you are going to need into the
> initramfs, and make sure mdadm is built static.)
>
> QUESTION: What's the difference between initrd and initramfs in
> practice. As I understand it initramfs is the newer one. I assume that
> means it's preferred? Or are there times when someone wants to still
> use an initrd?


AFAIK, initramfs is the newer preferred one and it's either one or the other
with initrd being seldom used these days if at all.

Many people still call it initrd even if int's initramfs in use - sort of a
slang thing

--
alan dot mckinnon at gmail dot com
 
Old 01-05-2011, 08:14 PM
Mark Knecht
 
Default Changing boot device with 2.6.36

On Wed, Jan 5, 2011 at 12:09 PM, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
<SNIP>
>
>
> AFAIK, initramfs is the newer preferred one and it's either one or the other
> with initrd being seldom used these days if at all.
>
> Many people still call it initrd even if int's initramfs in use - sort of a
> slang thing
>

I suspected as much. I was calling it initrd until I started reading
how to do one and found the new name.

I have run from the idea of doing one liked a scared little child at a
murder scene for the 10 years I've basically had Gentoo as my desktop
PC. After a couple of hours of using it I've started to think maybe I
should have one on every new system I do. After I got the rescue
environment with busybox going I could see why mdadm couldn't start
the RAID and knew how to fix it almost immediately. I was thinking
about how much time I've wasted on new bring ups where it cannot sync
the file system. Just being able to get around those sorts of problems
would have likely saved me days of time over the last decade.

Thanks!

- Mark
 
Old 01-07-2011, 07:47 AM
Jörg Schaible
 
Default Changing boot device with 2.6.36

Hi Dale,

Dale wrote:

> Jörg Schaible wrote:
>> that approves my tests ... :-/
>>
>> Had to boot this morning 5 times, since the root device switched
>> arbitrarily between sde3 and sdg3 and I've chosen by bad luck always the
>> wrong one. It seems there is also some timing involved regarding the
>> initialization of the available devices ... sigh.
>>
>> - Jörg
>
> I had to reboot last night and was in my BIOS looking for other things
> but did notice this feature. I have a setting in my BIOS that tells it
> what drive to look for to boot first. It's above the part where you
> tell it to boot CDROM, hard drive, floppy, ZIP and other bootable
> things. You may want to check and see if you have the same thing. Mine
> is called "hard disk boot priority". I'm not sure this will help but it
> couldn't hurt to check I guess.

The first device to try is my HD and as alternative I can only select the CD
drive anyway (which is deactivated). At boot time I can still switch into a
boot menu of the BIOS to select something else.

> I also noticed something else that may not be related. I enabled AHCI a
> while back and noticed it will not boot from a CD/DVD when in that
> mode. I have to set it back to IDE for it to be able to boot from other
> than the hard drive. Maybe if you set yours to AHCI, it will skip the
> external stuff like USB?

All of this is set to AHCI. And I rather not set this to IDE.

> I'm seriously pulling it out my butt here. I hope one of these will
> help. ;-)

What really annoys me is, that I had no problems with this in kernels before
2.6.35 :-/

Anyway, thanks for your help,
Jörg
 
Old 01-07-2011, 08:34 AM
"J. Roeleveld"
 
Default Changing boot device with 2.6.36

On Friday 07 January 2011 09:47:28 Jörg Schaible wrote:
> Hi Dale,
>
> Dale wrote:
> > Jörg Schaible wrote:
> >> that approves my tests ... :-/
> >>
> >> Had to boot this morning 5 times, since the root device switched
> >> arbitrarily between sde3 and sdg3 and I've chosen by bad luck always the
> >> wrong one. It seems there is also some timing involved regarding the
> >> initialization of the available devices ... sigh.
> >>
> >> - Jörg
> >
> > I had to reboot last night and was in my BIOS looking for other things
> > but did notice this feature. I have a setting in my BIOS that tells it
> > what drive to look for to boot first. It's above the part where you
> > tell it to boot CDROM, hard drive, floppy, ZIP and other bootable
> > things. You may want to check and see if you have the same thing. Mine
> > is called "hard disk boot priority". I'm not sure this will help but it
> > couldn't hurt to check I guess.
>
> The first device to try is my HD and as alternative I can only select the
> CD drive anyway (which is deactivated). At boot time I can still switch
> into a boot menu of the BIOS to select something else.

This will not affect the order the Linux kernel will identify and label the
devices.
It will only affect where the BIOS will look for boot-code.

Simply put, the following happens when a PC boots:

1) BIOS goes through its self-check

2) BIOS looks for boot-code on the devices it found in the order configured in
the BIOS (BIOS -Boot Order)

3) BIOS runs boot-code

4) boot-code starts the boot-loader (GRUB)

5) GRUB loads kernel into memory

6) starts kernel

7) kernel detects drives and assigns them names in order of finding them

At this point, it goes wrong as the drivers are not always identified in the
same order. From what it looks like, on the OPs system, the USB-subsystem is
scanned before the SATA-controller.
The easiest solution to this problem would be to ensure that the USB-subsystem
is not scanned before the boot-device is identified by the kernels boot-
process.

This can be achieved by configuring the USB-mass-storage support as a module.

Another option would be to patch the kernel to either support Labels natively
or to have it include a "scan harddisks in following order:...." option which
lists which harddisk-drivers (sata/ide/usb) are scanned and in which order.

--
Joost
 
Old 01-07-2011, 08:36 AM
"J. Roeleveld"
 
Default Changing boot device with 2.6.36

On Wednesday 05 January 2011 13:35:28 Dale wrote:
> Jörg Schaible wrote:
> > that approves my tests ... :-/
> >
> > Had to boot this morning 5 times, since the root device switched
> > arbitrarily between sde3 and sdg3 and I've chosen by bad luck always the
> > wrong one. It seems there is also some timing involved regarding the
> > initialization of the available devices ... sigh.
> >
> > - Jörg
>
> I had to reboot last night and was in my BIOS looking for other things
> but did notice this feature. I have a setting in my BIOS that tells it
> what drive to look for to boot first. It's above the part where you
> tell it to boot CDROM, hard drive, floppy, ZIP and other bootable
> things. You may want to check and see if you have the same thing. Mine
> is called "hard disk boot priority". I'm not sure this will help but it
> couldn't hurt to check I guess.
>
> I also noticed something else that may not be related. I enabled AHCI a
> while back and noticed it will not boot from a CD/DVD when in that
> mode. I have to set it back to IDE for it to be able to boot from other
> than the hard drive. Maybe if you set yours to AHCI, it will skip the
> external stuff like USB?

Dale, juust out of curiosity here.
Do you have your CD/DVD drive attached using a SATA-cable? Or using an "older"
IDE-cable?

I use AHCI in my BIOS and can boot from CD/DVD. But my DVD-drive is a SATA-
drive.

--
Joost
 
Old 01-07-2011, 09:32 AM
Neil Bothwick
 
Default Changing boot device with 2.6.36

On Fri, 07 Jan 2011 09:47:28 +0100, Jörg Schaible wrote:

> What really annoys me is, that I had no problems with this in kernels
> before 2.6.35 :-/

Have you tried diffing the configs to look for a potential cause?


--
Neil Bothwick

Top Oxymorons Number 12: Plastic glasses
 
Old 01-07-2011, 10:28 AM
Jörg Schaible
 
Default Changing boot device with 2.6.36

Hi Neil,

Neil Bothwick wrote:

> On Fri, 07 Jan 2011 09:47:28 +0100, Jörg Schaible wrote:
>
>> What really annoys me is, that I had no problems with this in kernels
>> before 2.6.35 :-/
>
> Have you tried diffing the configs to look for a potential cause?

Yes, but I could not detect anything related. It was a simple "make
oldconfig" and the diff displays nothing unexpected.

- Jörg
 

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