A little more follow up... it is only the Pi Zero which fails.
pi@raspberrypi:~/cec $ cat /proc/cpuinfo
processor : 0
model name : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS : 697.95
Features : half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb76
CPU revision : 7
Hardware : BCM2835
Revision : 900093
Serial : 00000000299ef634
Model : Raspberry Pi Zero Rev 1.3
pi@raspberrypi:~/cec $ echo 'scan' | cec-client -s -d 1
Illegal instruction
The Pi 3b does NOT give the same error.
Simon
pi@raspberrypi:~/cec $ gdb cec-client
GNU gdb (Raspbian 8.2.1-2) 8.2.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "arm-linux-gnueabihf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from cec-client...(no debugging symbols found)...done.
(gdb) r
Starting program: /usr/bin/cec-client
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
Program received signal SIGILL, Illegal instruction.
0xb6f9105c in ?? () from /lib/arm-linux-gnueabihf/libp8-platform.so.2
(gdb) bt
#0 0xb6f9105c in ?? () from /lib/arm-linux-gnueabihf/libp8-platform.so.2
#1 0xb6fde2e8 in call_init (l=<optimized out>, argc=argc@entry=1,
argv=argv@entry=0xbefff3e4, env=env@entry=0xbefff3ec) at dl-init.c:72
#2 0xb6fde3ec in call_init (env=<optimized out>, argv=<optimized out>,
argc=<optimized out>, l=<optimized out>) at dl-init.c:30
#3 _dl_init (main_map=0xb6fff978, argc=1, argv=0xbefff3e4, env=0xbefff3ec)
at dl-init.c:119
#4 0xb6fcea74 in _dl_start_user () from /lib/ld-linux-armhf.so.3
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)
Basic Raspbian install...
48ce9cf1a6781600d10dee46228920ef 2021-05-07-raspios-buster-armhf-lite.zip
or
b89314053308d03d1a9b48057e035588 2021-05-07-raspios-buster-armhf.zip
Plus...
4b9c978447e0c944495e35969f7c4abf cec-utils_4.0.4+dfsg1-2_armhf.deb
ca9c81dffae3aa2a672bd87f3fadca59 libcec4_4.0.4+dfsg1-2_armhf.deb
32b044852428290ab71b23d24f36c597 libp8-platform2_2.1.0.1+dfsg1-2_armhf.deb
pi@raspberrypi:~/cec $ cat /proc/cpuinfo
processor : 0
model name : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS : 697.95
Features : half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb76
CPU revision : 7
Hardware : BCM2835
Revision : 900093
Serial : 00000000299ef634
Model : Raspberry Pi Zero Rev 1.3
pi@raspberrypi:~/cec $ echo 'scan' | cec-client -s -d 1
Illegal instruction
pi@raspberrypi:~ $ cec-client
No device type given. Using 'recording device'
CEC Parser created - libCEC version 4.0.4
no serial port given. trying autodetect: FAILED
pi@raspberrypi:~ $ echo 'scan' | cec-client -s -d 1
autodetect FAILED
pi@raspberrypi:~ $ cat /proc/cpuinfo
processor : 0
model name : ARMv7 Processor rev 4 (v7l)
BogoMIPS : 38.40
Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt
vfpd32 lpae evtstrm crc32
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4
processor : 1
model name : ARMv7 Processor rev 4 (v7l)
BogoMIPS : 38.40
Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt
vfpd32 lpae evtstrm crc32
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4
processor : 2
model name : ARMv7 Processor rev 4 (v7l)
BogoMIPS : 38.40
Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt
vfpd32 lpae evtstrm crc32
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4
processor : 3
model name : ARMv7 Processor rev 4 (v7l)
BogoMIPS : 38.40
Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt
vfpd32 lpae evtstrm crc32
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4
Hardware : BCM2835
Revision : a020d3
Serial : 000000004ae2a734
Model : Raspberry Pi 3 Model B Plus Rev 1.3
