[coreboot] Time for a new project

Segher Boessenkool segher at kernel.crashing.org
Sun Apr 13 19:03:12 CEST 2008

> The problem is that the loader code will not change.
> When the loader reads the type value, it will differ depending on
> endianism.  As an example, 'CODE' will be equivalent to
> 0x45444F43 on a little endian machine, and 0x434F4445 on
> a big endian machine.  This causes obvious issues in the code.
> By dictating that all the header values should be in little endian
> we avoid this problem.

Either the code will use u32 everywhere, or it will use u8[4]
(or char[4]) everywhere.  Either way, it works fine; the second
option is better of course, since the binary will be more readable
(in a hexdump).

You have to be careful in your tools, so that cross-builds work

> Thats true.  But again, like I said, what concerns us is that endianism
> affects the order in which the bytes will be stored in the header

That depends on how *exactly* you define the SELF format.  Writing
a *proper* specification is a lot of work, indeed!

> The endianism is specified by the processor, not the software.

Not true.  There are *many* processors that can run either
little-endian or correct-endian: ARM, MIPS, PowerPC, ...

> A x86 is little endian, forever more.

Yeah, poor x86.

> And since v3 only works on an x86,

I hope to change that soon.

> we could ignore it for now.

No you cannot, if you're defining this new binary format.  Yet
another reason why you really shouldn't.

> But
> we know that the problem exists, and we might as well account for it
> now.  By specifying it as little endian, we do put other architectures
> at a disadvantage.  But none of those other architectures are in play
> for a very long time.  You have to play to your strengths.


What are you saying here?


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