Re: Re: [gentoo-user] /dev/sda* missing at boot

Re: Re: [gentoo-user] /dev/sda* missing at boot

[frares]

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Em 18/08/2011 16:08, András Csányi <sayusi.ando@gmail.com> escreveu:
> On 18 August 2011 18:59, frares@gmail.com> wrote:

> > Hi, guys
> >
> > It is a shame, I know, but after several years using Gentoo, it is the  
> first
> > time I try to build a kernel without "genkernel".
> >
> > And now I can't boot to that new kernel, it does not find (and really  
> do not
> > have a) /dev/sda* root partition ("real-root"); during the boot it  
> stops,
> > complaining about that, gives me the option to get a shell, from which  
> I am
> > able to see that there is no /dev/sda* .
> >
> > I have included everything SATA, so it looks like that is not a kernel
> > problem, but a initramfs issue, I guess.
> >
> > What am I missing?


> Why have you choose this way? I mean, non-genkernel way.


> --
> - -
> -- Csanyi Andras (Sayusi Ando) -- http://sayusi.hu --
> http://facebook.com/andras.csanyi
> -- ""Trust in God and keep your gunpowder dry!" - Cromwell



That's recommended in the new install manual:

http://www.gentoo.org/doc/en/handbook/handbook-amd64.xml?style=printable&full=1#book_part1_chap7

Look for item "7c". The alternative way is to use genkernel.

Francisco

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Re: Re: [gentoo-user] /dev/sda* missing at boot

[frares]

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Em 18/08/2011 16:13, Michael Mol <mikemol@gmail.com> escreveu:
> On Thu, Aug 18, 2011 at 2:59 PM, frares@gmail.com> wrote:
> >
> > Hi, guys
> >
> > It is a shame, I know, but after several years using Gentoo, it is the  
> first time I try to build a kernel without "genkernel".
> >
> > And now I can't boot to that new kernel, it does not find (and really  
> do not have a) /dev/sda* root partition ("real-root"); during the boot it  
> stops, complaining about that, gives me the option to get a shell, from  
> which I am able to see that there is no /dev/sda* .
> >
> > I have included everything SATA, so it looks like that is not a kernel  
> problem, but a initramfs issue, I guess.

> If you've got a SATA controller, no frills, then all you *really* need
> is AHCI. Build that into your kernel if you're worried about having
> the right modules in initramfs. You can break it out into a module
> later if you like. Opinions differ as to how much stuff should be
> broken into modules vs being built-in to the kernel. I tend to build
> in everything absolutely needed for boot, myself. Some people build in
> just about everything, and some people build in almost nothing.
> There's no "right" way for every use case.

> Also, check your BIOS to see if it's running your SATA controller in
> some kind of IDE emulation mode. If it is, disable that. (Some
> motherboards let you choose between "IDE" and "RAID", where "RAID" is
> AHCI mode. Others call IDE mode 'legacy', and still others might
> actually call the AHCI mode 'AHCI')

> Motherboards running SATA controllers in IDE emulation mode is an
> incredibly common thing:

> 17:18 beh
> 17:18 hda1 turned into sda1
> 17:19 IRule: Turn SCSI-generic support, or did you
> switch from legacy to AHCI in your BIOS?
> 17:20 shortcircuit: quiet, you

> --

> :wq


Thanks, gonna try it.

Francisco

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Re: Re: [gentoo-user] /dev/sda* missing at boot

[frares]

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Em 18/08/2011 23:27, Mark Knecht <markknecht@gmail.com> escreveu:
> On Thu, Aug 18, 2011 at 11:59 AM, frares@gmail.com> wrote:
> > Hi, guys
> >
> > It is a shame, I know, but after several years using Gentoo, it is the  
> first
> > time I try to build a kernel without "genkernel".
> >
> > And now I can't boot to that new kernel, it does not find (and really  
> do not
> > have a) /dev/sda* root partition ("real-root"); during the boot it  
> stops,
> > complaining about that, gives me the option to get a shell, from which  
> I am
> > able to see that there is no /dev/sda* .
> >
> > I have included everything SATA, so it looks like that is not a kernel
> > problem, but a initramfs issue, I guess.
> >
> > What am I missing?
> >
> > Thanks a lot
> > Francisco
> >
> > PS: my boot partition is sda2, sda3 is a swap partition, and everything
> > else is in sda4. sda1 is not used (up to now) and this is my grub.conf :
> >
> > title Gentoo Linux 2.6.39-gentoo-r3
> > root (hd0,1)
> > kernel /boot/kernel-genkernel-x86_64-2.6.39-gentoo-r3 ro root=/dev/ram0
> > init=/linuxrc real_root=/dev/sda4 vga=0x318 video=uvesafb:1024x768-32
> > nodevfs udev devfs=nomount quiet CONSOLE=/dev/tty1
> > initrd /boot/initramfs-genkernel-x86_64-2.6.39-gentoo-r3

> Maybe I'm missing the obvious here but have you taken a copy of
> whatever config file was used/generated by genkernel and used that as
> a jumping off point for building your own kernel. kernel's a kernel's
> a kernel. What it is capable of doing is in the .config file. If
> genkernel doesn't give you a .config file - I've never used genkernel
> so I don't know what it does - then assuming you have the feature
> turned on you can get the running config using zcat /proc/config.gz.
> Save that to a new .config file, put it in the kernel source directory
> and you should be good to go.

> You can also use zcat /proc/config.gz on the install CD kernel if yuo
> boot from that. Save it to a disk and use it as the basis for creating
> your own config.

> HTH,
> Mark



That's what I am doing right now. I am using genkernel to have something to  
boot on. Then I will try to find a way to optimize another one.

Thanks
Francisco

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Re: Re: [gentoo-user] /dev/sda* missing at boot

[frares]

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Em 19/08/2011 07:09, Mick <michaelkintzios@gmail.com> escreveu:
> On Friday 19 Aug 2011 03:27:23 Mark Knecht wrote:
> > On Thu, Aug 18, 2011 at 11:59 AM, frares@gmail.com> wrote:
> > > Hi, guys
> > >
> > > It is a shame, I know, but after several years using Gentoo, it is the
> > > first time I try to build a kernel without "genkernel".
> > >
> > > And now I can't boot to that new kernel, it does not find (and really  
> do
> > > not have a) /dev/sda* root partition ("real-root"); during the boot it
> > > stops, complaining about that, gives me the option to get a shell,  
> from
> > > which I am able to see that there is no /dev/sda* .
> > >
> > > I have included everything SATA, so it looks like that is not a kernel
> > > problem, but a initramfs issue, I guess.
> > >
> > > What am I missing?
> > >
> > > Thanks a lot
> > > Francisco
> > >
> > > PS: my boot partition is sda2, sda3 is a swap partition, and  
> everything
> > > else is in sda4. sda1 is not used (up to now) and this is my  
> grub.conf :
> > >
> > > title Gentoo Linux 2.6.39-gentoo-r3
> > > root (hd0,1)
> > > kernel /boot/kernel-genkernel-x86_64-2.6.39-gentoo-r3 ro  
> root=/dev/ram0
> > > init=/linuxrc real_root=/dev/sda4 vga=0x318 video=uvesafb:1024x768-32
> > > nodevfs udev devfs=nomount quiet CONSOLE=/dev/tty1
> > > initrd /boot/initramfs-genkernel-x86_64-2.6.39-gentoo-r3
> >
> > Maybe I'm missing the obvious here but have you taken a copy of
> > whatever config file was used/generated by genkernel and used that as
> > a jumping off point for building your own kernel. kernel's a kernel's
> > a kernel. What it is capable of doing is in the .config file. If
> > genkernel doesn't give you a .config file - I've never used genkernel
> > so I don't know what it does - then assuming you have the feature
> > turned on you can get the running config using zcat /proc/config.gz.
> > Save that to a new .config file, put it in the kernel source directory
> > and you should be good to go.
> >
> > You can also use zcat /proc/config.gz on the install CD kernel if yuo
> > boot from that. Save it to a disk and use it as the basis for creating
> > your own config.

> If you no longer use genkernel it is likely that you do not need an  
> initram.
> Build chipset and fs modules into the kernel. Other drivers you can  
> choose if
> you want to build as modules.

> --
> Regards,
> Mick


I the case I don't need a initram, I guess that the grub line for parameter  
passing to the kernel would be empty. Am I wrong?

I was just looking on how to build my own initram. What is it supposed to  
do anyway?

Thanks
Francisco

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Re: Re: [gentoo-user] /dev/sda* missing at boot

[Gregory Woodbury]

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On Fri, Aug 19, 2011 at 9:12 AM, <frares@gmail.com> wrote:

> Em 19/08/2011 07:09, Mick <michaelkintzios@gmail.com> escreveu:
> > On Friday 19 Aug 2011 03:27:23 Mark Knecht wrote:
>
> > > On Thu, Aug 18, 2011 at 11:59 AM,  frares@gmail.com> wrote:
> > > > Hi, guys
> > > >
> > > > It is a shame, I know, but after several years using Gentoo, it is
> the
> > > > first time I try to build a kernel without "genkernel".
> > > >
> > > > And now I can't boot to that new kernel, it does not find (and really
> do
> > > > not have a) /dev/sda* root partition ("real-root"); during the boot
> it
> > > > stops, complaining about that, gives me the option to get a shell,
> from
> > > > which I am able to see that there is no /dev/sda* .
> > > >
> > > > I have included everything SATA, so it looks like that is not a
> kernel
> > > > problem, but a initramfs issue, I guess.
> > > >
> > > > What am I missing?
> > > >
> > > > Thanks a lot
> > > > Francisco
> > > >
> > > > P.S.: my boot partition is sda2, sda3 is a swap partition, and
> everything
> > > > else is in sda4. sda1 is not used (up to now) and this is my
> grub.conf :
> > > >
> > > > title Gentoo Linux 2.6.39-gentoo-r3
> > > > root (hd0,1)
> > > > kernel /boot/kernel-genkernel-x86_64-2.6.39-gentoo-r3 ro
> root=/dev/ram0
> > > > init=/linuxrc real_root=/dev/sda4 vga=0x318 video=uvesafb:1024x768-32
> > > > nodevfs udev devfs=nomount quiet CONSOLE=/dev/tty1
> > > > initrd /boot/initramfs-genkernel-x86_64-2.6.39-gentoo-r3
> > >
> > > Maybe I'm missing the obvious here but have you taken a copy of
> > > whatever config file was used/generated by genkernel and used that as
> > > a jumping off point for building your own kernel. kernel's a kernel's
> > > a kernel. What it is capable of doing is in the .config file. If
> > > genkernel doesn't give you a .config file - I've never used genkernel
> > > so I don't know what it does - then assuming you have the feature
> > > turned on you can get the running config using zcat /proc/config.gz.
> > > Save that to a new .config file, put it in the kernel source directory
> > > and you should be good to go.
> > >
> > > You can also use zcat /proc/config.gz on the install CD kernel if yuo
> > > boot from that. Save it to a disk and use it as the basis for creating
> > > your own config.
> >
> > If you no longer use genkernel it is likely that you do not need an
> initram.
> > Build chipset and fs modules into the kernel.  Other drivers you can
> choose if
> > you want to build as modules.
>
> I the case I don't need a initram, I guess that the grub line for parameter
> passing to the kernel would be empty. Am I wrong?
>
> I was just looking on how to build my own initram. What is it supposed to
> do anyway?
>

The initramfs is a container for modules and stuff need to bring up the
system before the mounts of
/ and /boot.    If all the drivers are built-in to the kernel (or at least
the minimum required drivers are built-in)
then the initramfs isn't necessary.

Passing parameters to the kernel is a different issue entirely.

My grub.conf line is:

                kernel /vmlinuz-3.0.3-gentoo root=/dev/sda2
pata_it821x.noraid=1

with the pata_it821x driver built-in for the kenel to find a set of older
IDE drives on the IT8212 card I have installed.

IIRC the initramfs is built with the mkinitrd command.  I haven't had to use
it so I could be wrong.

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Re: Re: [gentoo-user] /dev/sda* missing at boot

[frares]

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Em 19/08/2011 10:48, Alan McKinnon <alan.mckinnon@gmail.com> escreveu:
> On Fri 19 August 2011 13:12:25 frares@gmail.com did opine thusly:

> > I the case I don't need a initram, I guess that the grub line for
> > parameter passing to the kernel would be empty. Am I wrong?

> Yes.

> Using or not using kernel parameters has nothing to do with whether
> you use an initramfs or not.

> It's the initrd line in grub you do not need.

> >
> > I was just looking on how to build my own initram. What is it
> > supposed to do anyway?

> First, it's initramfs (the previous incarnation was initrd). You
> should use the correct name.

> An initramfs is a filesystems image stored on disk in a place that
> grub can find. It contains a kernel, essential drivers and other bits
> and pieces. When booting, grub finds the image, bangs it into memory
> and instructs the cpu to start executing at a known point.

> Why is this useful?

> For Gentoo it usually isn't (there are times when it is - see below).
> Binary distros like Ubuntu and Fedora absolutely require this. These
> distros do not know what hardware you have and what drivers you
> require, so they supply drivers for everything. But Ubuntu cannot
> possibly compile into the kernel every possible driver you might need
> to boot as the list would be huge (every known floppy, CD, USB, every
> known MFM, IDE, SATA, SCSI, netboot, Fibre and more driver for a
> start), so what they do instead is probe the hardware at boot time,
> find out what you have, and load the driver modules you DO need.

> This is the problem. The kernel wants to load disk drivers so that it
> can access the disk and continue booting. Where are the drivers? Well,
> they are on the disk. Oops, circular problem.

> The difficulty is not finding and loading drivers, it's how do you get
> the disk driver off the disk before you have the disk driver in
> memory? (think chicken and egg here).

> An initramfs solves this nicely. Grub shoved a disk image into memory
> when it booted. The kernel knows how to access it's memory it doesn't
> need a driver for that. And now the files containing the needed
> drivers are on a virtual disk *in memory*. The kernel loads them, and
> can now access the real physical disks.

> Lots more complicated stuff then happens, like getting rid of the
> virtual filesystem from the initramfs and mounting the real filesystem
> from disk at /, but that's beyond the scope of this mail.

> Gentoo mostly doesn't need any of this because you do know your
> hardware and can just compile your disk drivers into the kernel - this
> is the very thing that Ubuntu cannot do.

> Some Gentoo users still need an initramfs, such as booting off drives
> in a RAID configuration. They need the RAID drivers first to read the
> disks so use an initramfs to fix this little problem exactly as Ubunut
> fixes their problem.

> Make sense?


Completely! Thanks a lot.

So I guess that my problem is to find an appropriate pair of driver and  
hard disk operating mode.

> --
> alan dot mckinnon at gmail dot com


Thanks again
Francisco

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