[Buildroot] Getting It into Compact Flash

[Buildroot] Getting It into Compact Flash

[Ted Wood]

OK Next question:

 

I've built a kernel image and a file system image.

 

I've manually installed Grub 2 and a grub.cfg file which looks like this:

 

menuentry 'Buildroot'

{

set root='(hd0,msdos1)'

echo 'Loading Kernel')

linux /boot/bzimage

echo 'Loading Root FS'

initrd /boot/rootfs.ext2

}

 

It starts up OK, loads the kernel and uncompresses it.

It mounts sda and sda1

Then "No filesystem could mount root, tried ext3 vfat msdos iso9660"

 

I've tried it with various different types of filesystem image (iso9660,
cramfs, ext2) and they all fail in a similar way...

 

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[Buildroot] Getting It into Compact Flash

[Richard Braun]

On Wed, Dec 12, 2012 at 04:12:49PM -0000, Ted Wood wrote:
> It starts up OK, loads the kernel and uncompresses it.
> 
> It mounts sda and sda1
> 
> Then "No filesystem could mount root, tried ext3 vfat msdos iso9660"

Buildroot doesn't take care of the partition table.

See http://lists.busybox.net/pipermail/buildroot/2012-August/057536.html
(and the next message for the unspoiled attached script).

-- 
Richard Braun

[Buildroot] Getting It into Compact Flash

[Richard Braun]

On Wed, Dec 12, 2012 at 05:22:26PM +0100, Richard Braun wrote:
> On Wed, Dec 12, 2012 at 04:12:49PM -0000, Ted Wood wrote:
> > It starts up OK, loads the kernel and uncompresses it.
> > 
> > It mounts sda and sda1
> > 
> > Then "No filesystem could mount root, tried ext3 vfat msdos iso9660"
> 
> Buildroot doesn't take care of the partition table.
> 
> See http://lists.busybox.net/pipermail/buildroot/2012-August/057536.html
> (and the next message for the unspoiled attached script).

If your problem has nothing to do with the partition table, feel free to
give us more information about it, like the boot log (so that we can see
what is actually mounted).

-- 
Richard Braun

[Buildroot] Getting It into Compact Flash

[Ted Wood]

> >-----Original Message-----
> >From: Richard Braun [mailto:rbraun at sceen.net]
> >Sent: 12 December 2012 20:49
> >To: Ted Wood
> >Cc: buildroot at busybox.net
> >Subject: Re: [Buildroot] Getting It into Compact Flash
> >
> >On Wed, Dec 12, 2012 at 05:22:26PM +0100, Richard Braun wrote:
> >> On Wed, Dec 12, 2012 at 04:12:49PM -0000, Ted Wood wrote:
> >> > It starts up OK, loads the kernel and uncompresses it.
> >> >
> >> > It mounts sda and sda1
> >> >
> >> > Then "No filesystem could mount root, tried ext3 vfat msdos
> >iso9660"
> >>
> >> Buildroot doesn't take care of the partition table.
> >>
> >> See
> >> http://lists.busybox.net/pipermail/buildroot/2012-August/057536.html
> >> (and the next message for the unspoiled attached script).
> >
> >If your problem has nothing to do with the partition table, feel free
> >to give us more information about it, like the boot log (so that we
> >can see what is actually mounted).
> >
> >--
> >Richard Braun

Boot Log:

RAMDISK: ext2 filesystem found at block 0
RAMDISK: Loading 2263KiB [1 disk] into ram disk.. done.
List of all partitions:
0800      7831152 sda    driver: sd
 0801      7825423 sda1 00000000-0000-0000-0000-000000000000
No filesystem could mount root, tried ext3 vfat msdos iso9660 Kernel panic -
not syncing VFS: Unable to mount root fs on on unknown block (1,0)


I also note that the Buildroot Kernel will boot OK into with my ext3 Yocto
Filesystem...

Would I be correct in thinking that the kernel is only configured for ext3,
vfat, msdos and iso9600 file systems?
And it is therefore not recognising the the ext2 FS generated by Buildroot?

[Buildroot] Getting It into Compact Flash

[Richard Braun]

On Thu, Dec 13, 2012 at 10:48:07AM -0000, Ted Wood wrote:
> Would I be correct in thinking that the kernel is only configured for ext3,
> vfat, msdos and iso9600 file systems?
> And it is therefore not recognising the the ext2 FS generated by Buildroot?

Ah yes, likely. Use make linux-menuconfig, go check that, and I suggest
you use ext4 with ext2/ext3 support if your kernel is recent enough
(>= 2.6.35 iirc), so you just have one option to rule them all and don't
waste more time on this issue.

-- 
Richard Braun

[Buildroot] Getting It into Compact Flash

[Ted Wood]

> >-----Original Message-----
> >From: Richard Braun [mailto:rbraun at sceen.net]
> >Sent: 13 December 2012 11:32
> >To: Ted Wood
> >Cc: buildroot at busybox.net
> >Subject: Re: [Buildroot] Getting It into Compact Flash
> >
> >On Thu, Dec 13, 2012 at 10:48:07AM -0000, Ted Wood wrote:
> >> Would I be correct in thinking that the kernel is only configured
> >for
> >> ext3, vfat, msdos and iso9600 file systems?
> >> And it is therefore not recognising the the ext2 FS generated by
> >Buildroot?
> >
> >Ah yes, likely. Use make linux-menuconfig, go check that, and I
> >suggest you use ext4 with ext2/ext3 support if your kernel is recent
> >enough (>= 2.6.35 iirc), so you just have one option to rule them all
> >and don't waste more time on this issue.
> >
> >--
> >Richard Braun

I went into linux-menuconfig and set up support for ext4 and ext3


I can't find any way of enabling the generation of ext3/ext4  File System
images.

[Buildroot] Getting It into Compact Flash

[Richard Braun]

On Thu, Dec 13, 2012 at 01:08:16PM -0000, Ted Wood wrote:
> I went into linux-menuconfig and set up support for ext4 and ext3
> 
> 
> I can't find any way of enabling the generation of ext3/ext4  File System
> images.

Read carefully what I wrote please: disable ext2 and ext3, and enable
ext4 (CONFIG_EXT4_FS) and the option to use the ext4 driver for ext2 and
ext3 too (CONFIG_EXT4_USE_FOR_EXT23). There is currently no way to build
an ext3 or ext4 image (you need to use tune2fs with some magic to enable
the new features), but with the configuration I'm suggesting, you'll
have good support for every ext file system.

-- 
Richard Braun

[Buildroot] Getting It into Compact Flash

[Ted Wood]

> >ext3 too (CONFIG_EXT4_USE_FOR_EXT23). There is currently no way to 
> >build an ext3 or ext4 image (you need to use tune2fs with some magic 
> >to enable the new features), but with the configuration I'm 
> >suggesting, you'll have good support for every ext file system.


OK. Got it. Understood. Thank you.

It now boots but does not open a login shell. 

menuConfig has a default login terminal ttyS0 - presumably this is for a
serial port?

Code is running on an i586 single board computer with keyboard and monitor
connected


I've tried building the code for tty0 and tty1.

[Buildroot] Getting It into Compact Flash

[Arnout Vandecappelle]

On 12/12/12 17:12, Ted Wood wrote:
> OK Next question:
>
> I?ve built a kernel image and a file system image.
>
> I?ve manually installed Grub 2 and a grub.cfg file which looks like this:
>
> menuentry ?Buildroot?
>
> {
>
> set root=?(hd0,msdos1)?
>
> echo ?Loading Kernel?)
>
> linux /boot/bzimage
>
> echo ?Loading Root FS?
>
> initrd /boot/rootfs.ext2
>
> }

  For an initrd, you should use a cpio filesystem rather than ext2:

- ext2 adds overhead that is completely unnecessary for a ramdisk;

- if you use anything else than static device management, the devtmps
will not be mounted automatically by the kernel; the cpio filesystem
adds a /init script that mounts it for you.

  I thought this was now clearly explained in the manual, is it not?

  Regards,
  Arnout

-- 
Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

[Buildroot] Getting It into Compact Flash

[Richard Braun]

On Thu, Dec 13, 2012 at 10:37:19PM +0100, Arnout Vandecappelle wrote:
> - if you use anything else than static device management, the devtmps
> will not be mounted automatically by the kernel; the cpio filesystem
> adds a /init script that mounts it for you.

The kernel has provided the ability to automatically mount devtmpfs for
quite some time now. He just needs to make sure the option is selected
in the kernel configuration.

-- 
Richard Braun

[Buildroot] Getting It into Compact Flash

[Arnout Vandecappelle]

On 13/12/12 23:04, Richard Braun wrote:
> On Thu, Dec 13, 2012 at 10:37:19PM +0100, Arnout Vandecappelle wrote:
>> - if you use anything else than static device management, the devtmps
>> will not be mounted automatically by the kernel; the cpio filesystem
>> adds a /init script that mounts it for you.
>
> The kernel has provided the ability to automatically mount devtmpfs for
> quite some time now. He just needs to make sure the option is selected
> in the kernel configuration.

  But it doesn't automount devtmpfs when the initramfs is mounted. That's
why fs/cpio/init exists.

  (Come to think of it, it is possible that an ext2 initrd is not 
considered the same as an initramfs and the kernel _will_ mount devtmpfs 
- I'm not sure).


  Regards,
  Arnout
-- 
Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

[Buildroot] Getting It into Compact Flash

[Ted Wood]

> >
> >  For an initrd, you should use a cpio filesystem rather than ext2:
> >
> >- ext2 adds overhead that is completely unnecessary for a ramdisk;
> >
> >- if you use anything else than static device management, the devtmps 
> >will not be mounted automatically by the kernel; the cpio filesystem 
> >adds a /init script that mounts it for you.
> >
> >  I thought this was now clearly explained in the manual, is it not?
> >

There is no reference to either cpio or devtmps in the manual.