Dear François-Xavier,
in message DA5CB450F843D611823E0002A5D4DB3C01FFD0B8@renexch1.rennes.thmulti.com you wrote:
Then I decided where to flash u-boot. On a ppc cpu, the processor first jumps at address 0xfffffffc. At this very address there is a branch instruction to a bootloader. For example, with the original bootloader > this
Please don't make such statements. They may be correct on your system (which obviously uses a IBM 4xx processor), but they are wrong on most other systems. For example, no Motorola PowerPC processor that I know of uses 0xFFFFFFFC as reset entry point. Nor does any ARM or MIPS based system.
Also, checking the register initialization may have worked in your case, but it does not help in the general case like when unknown board hardware (like a FPGA) needs to be initialized or set to a certain state. In such a case you are LOST without adequate documentation from the manufacturer.
On the other hand, there are usually other, better documented hardware solutions around :-)
Best regards,
Wolfgang Denk