recovery.img and recovery-from.boot.p

[Ron M]

Hi all,

I am trying to make sense of how the android system is made up w.r.t
to boot/kernel.
I have been looking at the .img files in the build (I built for the
"passion" device), and have been
googling around to find some more information about the various .img
files.

I ran into a nice HOWTO in
http://android-dls.com/wiki/index.php?title=HOWTO:_Unpack%2C_Edit%2C_and_Re-Pack_Boot_Images
, but I am afraid it is a little outdated:

I have several questions, but I will try to be brief, so I'll focus on
one of them, and if that works I'll
proceed to the next questions, all related to "Android bringup for
dummy embedded linux kernel experts".
I am fairly aware of differences between different linux
configurations, and I am very familiar with linux bringup concepts, so
I will just use common examples from the linux world as my
terminology. Hope it will be clear enough.

I understood that boot.img a combination of a kernel (e.g. bzImage in
linux) and an initial ramdisk (e.g. initrd.gz), wrapped by some
header, as common practice.

The aforementioned HOWTO says that the "recovery" image is built on
the same way, and that it is stored on the target's /system/
recovery.img .
I would assume that this would be compound of the ramdisk-
recovery.img, and some other kernel.
Now, the problem is that:
1. This /system/recovery.img does not exist from what I saw (on my
Motorola XOOM tablet)
2. What does exist is /system/boot-from-recovery.p , which is
created during the boot process in obj/PACKAGING/
recovery_patch_intermediates/recovery_from_boot.p .
I saw tons of posts referring to the files, all said that "in order to
replace the rescue disk image, this file needs to be renamed" - but I
am looking for a way to figure out what it is, and how to extract its
contents.
I assume /system/recovery.img is deprecated, is that correct?
3. I did not see any flash devices in /proc/mtd (which is strange).

I searched for hours before sending this post, so I would appreciate
your help.
If it is not the right place to ask the question please let me know -
I just assume this is a general android concept and not flash
specific.


Thanks,
Ron