Great detective work!
EDIT2:
In the previous post you were actually asking about where that function was called, and not the function itself. So the below story misses that point a bit.
The function usermapped_send_sysenter() is indeed called from MOD09_VM, as you said .
Looks like that SYSENTER instruction is in KERNEL:
$ LANG=C grep -obaP "\xbf\x22\x00\x00\x00\x8b\x45\x08\x0f\x34" KERNEL |cat -v
29487:M-?"^@^@^@M-^KE^H^O4
$ printf "%x\n" 29487
732f
$ cat KERNEL |xxd -g1 |grep -C1 ^00007320
00007310: 55 89 e5 53 8b 45 08 cd 22 89 d9 5b 5d c3 90 90 U..S.E.."..[]...
00007320: 55 89 e5 55 52 53 56 57 89 e6 ba 39 43 41 f0 bf U..URSVW...9CA..
00007330: 22 00 00 00 8b 45 08 0f 34 57 9d 89 d9 5f 5e 5b "....E..4W..._^[
I lifted the 'bf 22 00 00 00 8b 45 08 0f 34' hex string from the debugger log (in the previous post).
You can find it in Cutter Search too ("All maps"): It's in fcn.f0414320.
But Cutter doesn't show any X-refs for me, so it's a bit hard to identify what this function actually is. Maybe Cutter just can't find them, it doesn't always get everything right.
To clarify a bit, here's how it shows on the debugger log:
001b:f100132f BF 22 00 00 00 mov edi,00000022
001b:f1001334 8B 45 08 __ __ mov eax,dword ss:[ebp+08]
001b:f1001337 0F 34 __ __ __ sysenter
EDIT: Found the function. I was playing around with Minix cross-compiling a bit and the build script just finished.
The script left all these *.o crumbs in its directories, so why not take a look at them. And there it is:
$ pwd
/home/z/tmp/minix/obj.i386/minix/kernel
$ LANG=C grep -obaP "\xbf\x22\x00\x00\x00\x8b\x45\x08\x0f\x34" *.o
usermapped_glo_ipc.o:879:�"�4
The object is attached below if you want to take a look. The file is not stripped, so all the function names show up in Cutter nicely. The function in question (that corresponds to debugger log) is named usermapped_send_sysenter().
(There were a number of other similarly named functions that have that sysenter instruction too).
Btw, on my old C2Q Ubuntu host, a cross-compiled build of Minix3 took about 4 hours & 5.1GB disk space.