Qi multi-boot: will it be supported?

Mike (mwester) mwester at dls.net
Fri Oct 31 17:57:13 CET 2008

Marco Trevisan (Treviño) wrote:
> Hello, actually I'm generally turning on my phone trough an uBoot that
> I've configured to support booting from about 4 different distro using
> one uSD ext2 partition for all the kernels (named like
> "uImage-<distro>.bin") and 4 ext2 partitions for all the distros
> installed (Om2008, FSO, Debian, Qt Extended...).
> Also if I generally use the first one, I'd like to keep the ability of
> booting in a such way other distros using Qi too.
> If I've not read(/remember) wrong, Qi actually supports just booting
> from flash and from uSD (keeping the default way: one partition for
> kernel, another for the rootfs), but will it ever support a multi-boot
> like the uBoot does (with a configurable menu)?

This sort of functionality should be handled by a special kernel/rootfs.

OE already has support for this for other devices, and the current
kernel/hardware also has full support for this, so it's just a matter of
doing the work to build it.

What you describe is minimal support.  What I'd like to see would be a
set of "advanced" or "developer" configurations, that would allow (for
example) the kernel to be pulled in via NFS, or TFTP.  We should explore
using loopback mounts for the rootfs so that the SD card can be entirely
VFAT with the rootfs being a 128MB file image -- this might be slow but
it would allow a completely different set of (non-technical) users to
install and upgrade without requiring anything more than a Mac or a
Windows box that can read/write an SD card.

We have 4MB of flash for the kernel -- a minimal solution should be able
to fit such a kernel with initrd easily, leaving the entire rootfs
portion of flash exactly as it is today -- with the exception that such
a kernel would actually read the real kernel from the jffs2 rootfs
(which would make simple upgrades of the kernel easier, too...)

The benefits of such an approach are obvious; the only real drawback is
that it would be slower than Qi booting the real kernel directly.  But I
think that can be fixed too.

Mike (mwester)

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