[U-Boot-Users] New x86 board booted...now the hard part

Daniel Engström
2003-05-26T06:35:20Z

On 2003.05.23 21:00 Marc Singer wrote:
> Yipee! It boots.
Very good, now there are three of us.

> 1) Daniel, do you think that the 'fs' overrides in mem_init are
> necessary when ds == fs?
No, that's a left-over from AMDs 16bit code kit which need to use segment
overrides.

> 2) How would you expect to override mem_init on another x86 board?
Conditional compilation of sc520_asm.S it is, after all, sc520-specific.
The defines in sc520_asm.S and sc520.c are not there yet, but they should
look like most othe U-boot code:

#ifdef CONFIG_SC520

.....

#endif

I think it is cleaner to do this kind of things in the makefile, but it is
not
how the U-boot amkefiles are done.

> It seems to me that we'd be better off with a BSP entry point for
> RAM initialization that calls the appropriate library
> function(s).

mem_init is the BSP entry point for RAM initialization. Calling library
functions
before mem_init is done is not advisabe.

> 3) We ought to be able to share serial driver code between x86 and
> the risc processors as long as we abstract port accesses the
> way that the Linux kernel does. Has this been discussed?

Sure, we should be able to share. No, I have not investigated how that
would be done.
When I started the 386-port, I looked in a few directories under cpu/* for
what
cpu/i386 should contain. All CPU-subdirs I checked contined a serial
driver, so I
borrowed a 16550 version (from the 405GP i think) and included it slightly
modified
in cpu/i386.
/Daniel