[LinuxBIOS] Fitting larger flash chips to accomodate a kernel

Phil Endecott spam_from_linuxbios at chezphil.org
Sat Sep 30 15:23:37 CEST 2006

Dear LinuxBIOS experts,

I note the comment on the web site saying that most motherboards have 
only a 512 kbyte flash chip, which isn't enough for a compressed 
kernel, and so LinuxBIOS is normally used with a bootloader like FILO 
to load a kernel from an IDE device or whatever.

But larger flash chips are available.  For example, my VIA board has a 
512k SST chip for which pin-compatible 1M and 2M parts are available 
(but apparently no larger than that).  So my first question is, will 
higher-capacity flash chips "just work", or does the motherboard design 
limit them to the flash size that they are supplied with?  If it is 
possible to fit a larger chip the next question is whether these are 
easy to obtain in small (e.g. one-off) quantities.

Assuming that this is possible, let's say that I build a kernel 
containing only minimal drivers for the framebuffer and ethernet - no 
IDE etc, and maybe use the "Linux-Tiny" patch.  I wonder how much space 
would then be left for an initrd.  Ideally I would like to fit a single 
executable of maybe a few hundred kbytes uncompressed which is run 
instead of init (this is a for fixed-purpose box).

This is a very appealing way to use cheap PC hardware in fixed-purpose 
applications, if it can be done.  Maybe other readers are already doing 
this sort of thing?

Many thanks for any advice, or pointers to existing docs.



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