On Jul 21, 2014, at 2:35 AM, Alan Barrett <a...@cequrux.com> wrote:
> On Sun, 20 Jul 2014, Matt Thomas wrote:
>>> - how sysctl hw.machine_arch should be handled
>>
>> Right now it return the MACHINE_ARCH the executable was built for via an ELF
>> note.
>
> I'd expect sysctl hw.something to report information about the hardware
> that's in use, or perhaps the hardware that the kernel was built for. It
> seems weird to report information about how the currently running executable
> was built.
That's what hw.model does. hw.machine_arch is really an ABI indicator. Note
we change hw.machine_arch for compat_netbsd32.
> Perhaps we need different sysctl nodes to report the kernel's idea of
> MACHINE_ARCH and the userland executable's idea of MACHINE_ARCH.
I don't think so.
One reason for the various MACHINE_ARCH for earm is that earm{,hf}eb and
earmv7{,hf}eb, respectively, are binary incompatible (instructions have
different byte ordering, BE .vs. LE). Once I had to have earmv7{,hf}eb as a
distinct MACHINE_ARCH as well as earmv4 for pre-armv5te machines, it seemed
wrong to not have earmv7{,hf}. And if I had that, why shouldn't there be
earmv6{,hf}{,eb}?
