Re: Some questions about build.sh, machine, -u and tools

[Martin Husemann <martin%duskware.de@localhost>]

On Wed, May 05, 2021 at 12:57:21PM +0200, Rocky Hotas wrote:
> Ok! Even if two MACHINEs with different ABIs or endiannes have really
> few common features, maybe just the commercial brand and the
> partitioning scheme.  Sorry, this is extreme of course, but the common
> MACHINE idea still looks weird to me.

No, but you may have the choice wich kernel/userland you want to run
on the same physical hardware. An example is my cubietruck:
I run it big-endian as:

[~] martin@space-truckin > uname -p -m
evbarm earmv7hfeb

but most people use exactly the same hardware to run earmv7hf (little endian)
instead.

On this board the difference is a simple "set endianess" instruction early
in the kernel, but on some other machines it is a physical jumper on the board.

This is not a very typical case though.

The "compat" cases are more common: on arm machines you can execute
binaries for eabi (the default) and oabi. On aarch64 machines you could
run aarch64 (native 64bit), eabi (new 32bit abi) or oabi (old 32bit abi).

On mips it is o32, n32 or n64. Most popular case is amd64 kernels that also
can execute i386 userland.

But IMHO it is best to keep out this "compat" type of things when thinking
about native MACHINE and MACHINE_ARCH.


I guess now you see the complex spread sheet and understand why you have
been confused initally - hope it got better during this thread ;-)

Martin