Re: Can anyone boot a system using btrfs root with linux 3.14 or newer?

Marc MERLIN
2014-04-23T22:03:12Z

On Thu, Apr 24, 2014 at 12:54:57AM +0300, Пламен Петров wrote:
> > It may help to look up what error -38 translates into for that mount error.
>
> My searches so far failed to return anything useful to solving this problem.

Yeah, I searched before you :) this would require reading the kernel source
to track down -38.
(not hard, I just didn't do it)(

> The initrd way will require some reading up on my part - so will have to wait for tomorrow.

On debian, I just have to run this:
update-initramfs -v -c -k `grep linux-source debian/changelog | awk '{ print $1 }' | sed "s/linux-source-//"`

Then see /etc/initramfs-tools/initramfs.conf
but the defaults should work

Running update-grub2 should give you something like this:
echo 'Loading Linux 3.12.7-amd64-i915-preempt-20131107 ...'
linux /vmlinuz-3.12.7-amd64-i915-preempt-20131107 root=/dev/mapper/cryptroot ro rootflags=subvol=root cryptopts=source=/dev/sda4,keyscript=/sbin/cryptgetpw,discard usbcore.autosuspend=1 pcie_aspm=force i915.i915_enable_rc6 =7 i915.i915_enable_fbc=1 i915.semaphores=1 i915.lvds_downclock=1 acpi_osi=Linux acpi_backlight=vendor
echo 'Loading initial ramdisk ...'
initrd /initrd.img-3.12.7-amd64-i915-preempt-20131107

> > You don't have to build a
> > new kernel or make btrfs a module, just mounting a working initrd and then
> > trying this again with userland tools will help debug.
> > (alternatively, rescue boot media with your kernel would work too, but that's
> > likely more work to build than an initrd)
>
> Not more work - just replaced the kernel on the setup/rescue media with mine and the result is the same - see attached image file.

That's not what I meant, I meant a rescue media that boots another
filesystem than you root filesystem.
Then from there, you can use normal userland tools to manually mount your
root filesystem and/or see errors.

Marc
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