Hi Vlad, Hi list,
see inline comments.
On mer, 2008-04-16 at 14:47 +0300, Vlad Lungu wrote:
Luigi 'Comio' Mantellini wrote:
Hi Guys,
..
[0xbe000000 -> 0xbfc00000 ] JFFS2 root [0xbfc00000 -> 0xbfe00000 ] U-BOOT code [0xbfe00000 -> 0xbfffffff ] DATA
So you have 16+12Mo then u-boot then 2 Mo left.
Yes. :)
Into the JFFS2 filesystem there are the Kernel images and a lot of spare datas.
That's a rather big JFFS filesystem. Do you plan booting from it? Isn't it rather slow? It would take a few seconds (5-10) to scan the FS on this under U-Boot. I would recommend two strategies here:
I know that the JFFS2 is rather slow, but I have this constraint on my application. The kernel images are provided as a big all-in-one file that contains the kernel and the rootfs (which will mounted via a loopback device). Unfortunately I cannot change this logic because a lot of user-space software (made by external providers) assumes a big images repository to store the monolithic images.
-put the uImage directly in the NOR flash. Maybe in those 2 Mo at the end or somewhere else. Update it from Linux or if you screw up, from the network. -create a smaller partition (like 4Mo) and keep two kernels there, main and spare. Mount it under /boot in Linux.
I cannot follow these solutions because I need to keep monolithic images (large about 8-10 MB) without explode them.
Boot from there. Use the rest of the available space as root with the MTD concat driver but don't touch it from U-Boot.
The JFFS2 partition will not contain the ready-for-use rootfs but monolithic images that will be mounted using the loopback devices. This is a constraint of my application :S and I cannot change it.
Will boot much faster than from a 28Mo partition, you can use *summary* information on root (not supported in U-Boot) for faster mount in Linux, more versatile than uImage in NOR (you can have 1 or more spares depending on kernel sizes and partition size).
Can you explain this point?
How I can say to U-boot to consider the two flashes as a single space of memory (in order to place a big JFFS2 filesystem)? In Linux I can achieve this using the MTD Concat driver but I don't understand How I can do in U-boot.
What you are asking could be already possible, or require just a few modifications, but you have to ask yourself: do I really HAVE to do this?
The answer is pretty simple: the flash layout is a project constraint :D. I know that this approach is very slow, but the target application is a device that should be rebooted about once in a year.
Thanks a lot for your observations.
ciao
luigi
Regards, Vlad