[Toybox] [PATCH] strace: fix arm64 test.

[enh]

On Mon, Nov 27, 2023 at 3:32 PM Rob Landley <rob at landley.net> wrote:
>
> On 11/27/23 17:16, enh via Toybox wrote:
> > We're not specifically looking for armv8; we want any aarch64.
> >
> > I've also changed the 32-bit arm test because (a) Linux doesn't
> > support arm32 OABI any more, (b) it's clearer this way that 32-bit
> > armv8 still belongs in this branch, and (c) __arm__ and __aarch64__
> > are the usual spellings everywhere. (Sure, the latter is ugly, but
> > we have __i386__ rather than __x86__ one line later anyway! I still
> > have to grep AOSP for mistaken uses of the non-existent __x86__ on
> > a regular basis. And don't get me started on __riscv and __riscv_xlen!)
>
> Did you see my Nov 18th blog entry about "linux32" making my new pi-alike say
> "armv8l" instead of "armv7l"?
>
> There was no non-64 bit armv8. Moving to 64 bit was what armv8 introduced. The
> last 32 bit architecture was armv7.

i have a phone in my pocket that says you're wrong :-)

(this is what aarch32 is --- it's 32-bit armv8. there's no 32-bit armv*9*[1].)

funnily enough, i'm starting to have a problem with third-party open
source projects that don't believe there was 32-bit arm before armv8
(because they don't see armv7 any more), so they'll unconditionally
use new 32-bit armv8 instructions and go boom on armv7.

> I had to add a second override, and then
> teach the build to lie extra with a non-matching --host in order to get 32 bit
> hosted arm toolchains built for the next release.
>
> All the personality(PER_LINUX32) syscall _does_ is get uname and /proc to
> lie-to-autoconf about the architecture! It doesn't stop you from launching new
> 64 bit executables, or change memory mappings or CPU flags or anything. It just
> makes the queries return different info... and they got it wrong.
>
> Sigh. I removed my horrible #ifdef stack from uname because I thought linux32
> covered it, but I hadn't tested other host architectures...
>
> Rob

___
1. not to be confused with the 32-bit-only arm9, of course. don't get
me started on "when marketing gets involved in naming things"...