Bug#735092: flash-kernel: add Raspberry Pi support
On Sun, Jan 12, 2014 at 07:01:36PM +0000, Ian Campbell wrote:
> On Sun, 2014-01-12 at 19:24 +0100, Karsten Merker wrote:
> > On Sun, Jan 12, 2014 at 06:00:24PM +0000, Ben Hutchings wrote:
> > > On Sun, 2014-01-12 at 18:34 +0100, Karsten Merker wrote:
> >
> > > > The attached patch adds Raspberry Pi support to flash-kernel.
> > [SNIP]
> > > So the boot partition is mounted at /boot? Doesn't that make it
> > > impossible to install packaged kernels (as dpkg needs to create hard
> > > links)?
> >
> > Installing a kernel package (locally built using make-kpkg) with
> > a VFAT /boot does not show any problems here:
>
> The normal way of dealing with this is to not have the bootloader
> partition mounted on boot, this is described in flash-kernel via the
> Boot-Device field. I think this should be honoured for Rpi too.
> Rpi-ConfigTxt-Path would then be relative to this device.
Having the vfat boot partition as /boot is the standard way in
Raspbian (Debian/armhf rebuild for the Pi/armv6, "official" OS
distribution for the Pi) and is described this way in all user
documentation for the Pi. This is also expected by other
software, in particular the firmware update mechanism, which
expects the firmware image to be at
/boot/bootcode.bin, as well as by the Raspberry Pi foundation's
kernel updates (which do not come as a Debian kernel package).
Not mounting the vfat boot partition at /boot would of course be
technically possible, but nobody actually does that on a Pi
and it would pose several problems:
- The firmware update mechanism would have to be changed. This is
outside the scope of Debian and as installing firmware updates
is something that happens rather frequently on the Pi, that
must work without problems.
- All the Pi user documentation would have to be changed, which
is also outside the scope of Debian.
- In case the vfat boot partition is not mounted at /boot,
the firmware cannot anymore directly boot the /boot/vmlinuz-*
and /boot/initrd.img-* files from the kernel package.
That would therefore require copying the files from /boot
to the actual vfat boot partition.
As having the vfat boot partition mounted on /boot is the
actual default case, flash-kernel would have to handle this as
well. This means either special handling depending on whether
the vfat partition is at /boot or not, or generally copying the
kernel to the vfat partition under another name. The latter
would in the case vfat-at-/boot result in having the kernel and
initrd twice on the already quite small system vfat partition,
which is a route I would like to avoid.
All things taken together I think that we should simply
accept that the vfat boot partition gets mounted at /boot
on the Pi and use it this way.
Regards,
Karsten
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