On Wednesday 25 January 2012 22:29:16 Marek Vasut wrote:
On Wednesday 25 January 2012 21:56:37 Marek Vasut wrote:
On Wednesday 25 January 2012 19:20:01 Marek Vasut wrote:
So why not just replace the bootloader right away?
Booting process on n900:
- Omap bootrom
- Nokia X-Loader
- Nokia NOLO Bootloader
- Linux kernel
...
To make it clear, I own N900 myself ;-)
Nokia X-Loader and NOLO are stored in first nand part. It has size 128kB. Nokia X-Loader is signed (size 14.5kB), so cannot be replaced. NOLO bootloader is not signed (so theoretically can be replaced), but size is limited to 113kB. I do not know how to compile U-Boot binary with size < 113kB...
Size of part where is stored linux kernel has 2MB and it is enought for U-Boot with kernel image (~200kB + ~1.6MB). Also U-Boot can boot kernel from eMMC/SD.
You didn't answer my question, so again ... why can't you replace NOLO? Because there's the 113kb limit? Use SPL then.
I only tried to boot U-Boot in qemu wich increased boot part - but not worked. (NOLO in qemu can boot u-boot without problems). So NOLO do some extra work - which I do not know... Also limit is problem to test on real n900.
What do you mean? Did you crack yours open? Can you connect JTAG to the device? I didn't check on mine.
I have no idea if N900 has JTAG. And I think that nobody cracked X-Loader yet.
NOLO bootloader can be replaced/flashed via flasher-3.5 app throw USB. Also when NOLO is damaged (or cleared/replaced) it can restored - coldflashed again via flasher-3.5.
What I tried: I created mtd image where was X-Loader, NOLO and U-Boot. QEmu RX51 successfull booted this image and I got serial console and video screen output.
But when I created mtd image where was only X-Loader an U-Boot, QEmu RX51 was unable to boot (it freezed).
So NOLO executing some code which inilialize board or someting else which must be done in U-Boot board code. There is no documentation or info about NOLO, so I cannot create working NOLO replacement.