some question about / adding commandline files from rootfs

Werner Almesberger werner at
Tue Aug 26 22:51:05 CEST 2008

Andy Green wrote:
> Instead of loading the full kernel size in one call, Xiangfu can make a
> while() loop there loading 64KByte units for example, and inside the
> loop we check for AUX press.

Good idea. And we just don't care about NOR in qi, eliminating the
"AUX still pressed from selecting NOR" case.

  If seen we always abort the loop and jump
> to the last kernel source for the board, which is the backup one (and no
> longer look for AUX).

Jumping to the last would force you to use NAND for the backup system.
Better just skip the first group, so that you can also have the backup
system on SD. You get an automatic fallback to NAND anyway, by removing
the SD card.

> I just see it as more special pleading for NAND, it is "unusual file
> system".  But, large NAND is currently a fact and then it means we ought
> to have fs for it that does wear levelling.  By default that is going to
> be jffs2.

Alright, having a "real" file system there is certainly nicer for
the user, although it makes the task quite a bit harder for qi.

> Many other users now are booting SD
> for Debian and other rootfs and I didn't notice complaints about insane
> speed loss.  So I think it is OK for customers.

Perfect. Let's treat GTA02 and GTA03 the same then. Their different
unbricking mechanisms are a second-order problem.

> Huh?  No Qi sythesizes a commandline anyway based on board and kernel
> source, so there's no special case.  The synthesized commandline will
> continue to be what you get in the absence of the rootfs commandline
> file, and I expect we will not create a commandline file by default even.

Sounds good. As long as one is happy with qi's default, there's no
need to override it.

> What I meant is that we do not want function of backup system to have
> dependency to anything it doesn't have to... there's zero legitimate
> case for end user to touch backup kernel commandline.

Hmm, whenever the word "NOR" comes up, you remind me of its read-only
nature. There's also zero legitimate case for end users to ever have
to touch the NOR. Yet here we are, plotting massive changes that
completely rearrange that little world, even less than two months
after selling the first GTA02 :-)

If we already have a real file system to load the kernel from, it
would be pretty easy to also search it for the command line at the
same time, thus making all cases (SD-ext2, SD-FAT, and NAND) look
the same.

- Werner

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