5 sec boot

[Deepak Saxena]

On Oct 04 2008, at 15:49, Mitch Bradley was caught saying:
> c) Raw FLASH read time maxes out at 20 MB/sec.  But you don't get that  
> speed from the filesystem; JFFS2 is good for between 5 and 10 MB/sec.
>
> Considering all the intricacies of JFFS2, my best guess is that it's  
> going to be close to a wash whether the kernel + initrd is stored in  
> compressed or uncompressed form.
>
> OTOH, if the kernel + initrd were in a separate partition in e.g. romfs  
> format, where OFW could just blast them into memory without doing JFFS2  
> node processing, we could probably get close to the 20 MB/sec speed.

We can probably just get away with making all of /boot into a
romfs; however, do we even need to bother with a filesystem 
representation of the images?  We could have four partions 
(kernel0, kernel1, initrd0, initrd1) that contain the binary 
data for current and alternate images and some sort of way
to tell which one is current and which one is alternate.

~Deepak

-- 
Deepak Saxena - Kernel Developer - dsaxena at laptop.org