Bug#667681: Updated patches for Dreamplug / Marvell Kirkwood FDT
On Wed, Jun 20, 2012, Ian Campbell wrote:
> Are you suggesting that I should move the non-flash-kernel related
> content of /dev/sdb1 (e.g. vmlinuz, initramfs etc) to /dev/sdb2:/boot
> and remove sdb1 from the fstab, leaving it unmounted the majority of the
> time?
Exactly; also it should also keep working if you leave your system
untouched (if you keep /dev/sdb1 in fstab and if f-k tries to mount it
in /tmp to update boot files, it should just get bind-mounted
automatically).
> I'm happy to do that, just want to make sure I understand before I start
> moving stuff about.
Yup; it's also best if you have some recovery mechanism -- like being
able to pull the SD card and changing it from another device -- and some
debug mechanism -- like serial console over mini-USB.
> FYI /boot is 205M on this system (I don't recall if I partitioned it, or
> if the installer did it or if it came that way), so I'm not worried
> about space constraints (205M is bigger than the whole disk on my last
> Pentium based firewall machine ;-)). I think the original partition was
> VFAT though so that concern is valid.
Yup; I'm mostly concerned about the ext2 which is fragile on abrupt
shutdowns.
> It is possible that other DP users will want /dev/sda* (the internal
> sdcard) instead of /dev/sdb* (the external sdcard). Can I express sda vs
> sdb in the flash-kernel db somehow?
Ah, yes; that's indeed a problem. That means we need some config file
to override the boot device (ideally an installer would create this file
for you). This is currently missing in flash-kernel, but here I think
it should allow overriding parts of the machine db entry.
> Looking at my sda it seems the partitioning scheme used by the supplier
> there is 100M VFAT + 3.9G EXT.
Right; first partition as a small vfat is typically what I expect; it's
more reliable than ext2 but doesn't support links, also 100M is a more
serious space constraint (especially if initrds get large and kernel
versions pile up).
> There is also some /dev/mtd devices but I think they are tiny SPI things
> and not useful for booting.
Hmm ok; in terms of size, some Kirkwoods come with a full Debian or
Ubuntu rootfs in flash, I think some 512 MiB or so of flash were enough
to do this, but I've had various issues with ubifs on a device here that
kind of scared me away of it. It's probably all fixable, but the
serious issues in the kernel and userspace tools led me to think it
wasn't a good option when compared to SD card.
--
Loïc Minier
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