Adventures with Binfmt_misc...

[knc1]

That is the important finding.

That it can be made to work even though the kernel that is running the module was not built for that purpose.

Mind is still in a deep fog, but play with od a bit.
An example of /bin/chrt in the K3-3.2.1 file (this can be done on your host system):

core2quad bin $ file chrt
chrt: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.14, not stripped
core2quad bin $ od -a x2 -t x1 chrt | less
0000000 del   E   L   F soh soh soh nul nul nul nul nul nul nul nul nul
         7f  45  4c  46  01  01  01  00  00  00  00  00  00  00  00  00
0000020 stx nul   ( nul soh nul nul nul   l ack nul nul   4 nul nul nul
         02  00  28  00  01  00  00  00  6c  86  00  00  34  00  00  00
0000040   h syn nul nul stx nul nul eot   4 nul  sp nul bel nul   ( nul
         68  16  00  00  02  00  00  04  34  00  20  00  07  00  28  00
0000060  gs nul sub nul soh nul nul   p nul dc3 nul nul nul dc3 nul nul
         1d  00  1a  00  01  00  00  70  80  13  00  00  80  93  00  00

Pick a few that you have in both the Amazon image build and in the Buildroot output. Avoiding links to busybox <[:]

What is needed is to find a distinguishing byte sequence so that the binfmt_misc offset/string/mask can be set to tell the difference.

objdump, with selection of options, can help, as in:

core2quad bin $ objdump -s -h chrt | less

chrt:     file format elf32-littlearm

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .interp       00000013  00008114  00008114  00000114  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  1 .note.ABI-tag 00000020  00008128  00008128  00000128  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA

The .interp section should alway be the first, which **might** mean that its file offset will always be the same (114).

I included the .note.ABI-tag section because that may be a good place to put our AmazonHack mark if we need one.

Using readelf, we can get another view of the same information:

core2quad bin $ readelf  -x 1 chrt

Hex dump of section '.interp':
  0x00008114 2f6c6962 2f6c642d 6c696e75 782e736f /lib/ld-linux.so
  0x00008124 2e3300                              .3.

core2quad bin $ readelf  -x 2 chrt

Hex dump of section '.note.ABI-tag':
  0x00008128 04000000 10000000 01000000 474e5500 ............GNU.
  0x00008138 00000000 02000000 06000000 0e000000 ................

I admit, I have never done this before, and we may have to stumble into the actual procedure to make it work.

Then in the "wrapper script" that binfmt_misc calls would use a utility to list the "NEEDED" library names and build the options to our set in /mnt/us

[twobob]

Hokay. sounds good. I will have a dig then