I have install, on my embedded system, [...]
This platform (Geode LX + CS5536) is well supported by coreboot, and several similar mainboards are already working well, but some code and data files will still be needed to make this specific mainboard work.
SST49LF004B is a FWH type flash chip, and because it is in a socket it is easy to replace with a larger flash chips. There are compatible flash chips up to 16 Mbit (2Mbyte) in size, which is enough room for a Linux kernel.
Ok, Yes I thik that I can mount, for example, the SST49LF016C. (16Mbit)
After the installation can I "reinstall" my old bios? How?
The program flashrom (http://www.coreboot.org/Flashrom) can be used to reprogram the contents of flash chips from Linux. But we strongly recommend you to buy several extra flash chips, so that you can swap between your factory BIOS and coreboot while developing. This is a nice idea: http://www.coreboot.org/Image:Pushpin_roms_2.jpg
That's right! I will buy a extra flash chips, and, if possibile, a external hw for download/reset the firmware.
If you have some more money for the project it is nice to work with a ROM emulator, but the cheapest ones we know cost 150-200 EUR or so.
Sorry but... What is a Rom emulator? Can you post a sample link?
If you want to work on adding support for this mainboard I suggest starting with the code for the ALIX boards, they may be similar and are well supported.
My difficulty is that i start from zero. For example, I have see on a ALIX tutorial page (http://www.coreboot.org/PC_Engines_ALIX1.C_Build_Tutorial) but I don't find any sample or howto for build the firmware... How I can make for build a firmware with a linux kernel and after dowload it on a flash chips?
I can following this howto... ? (http://www.coreboot.org/AMD_Geode_Porting_Guide)
Thank you for your patience and your collaboration. Davide