[OE-core] pseudo: host user contamination

[Andre McCurdy]

On Sat, Mar 24, 2018 at 12:24 PM, Seebs <seebs at seebs.net> wrote:
>
> I didn't see a qualifier about it being only on a 32-bit architecture,
> it just says "EABI".
>
> But in general, this is the reason that musl's ability to work doesn't
> buy us guarantees; musl doesn't have to *interpret* the arguments. So
> for instance, they could just pass "the same arguments" for
> SYS_readahead, we couldn't. (If we needed it, which I don't think we
> do.)

Right. The musl example is to show how it's possible to transparently
intercept and pass on any call to the syscall() ABI without
interpreting anything.

> Similarly, they don't have to do Fancy Complicated Fixups around their
> system calls which can break weird register conventions. Consider:
>
>> >        On a few architectures, a register is used to indicate
>> > simple boolean failure of the system call:  ia64
>> > uses r10 for this purpose, and mips uses a3.

Those details are all taken care of within the libc implementation of
syscall(). It's not something we need to care about at all in a
wrapper for it.