Jetson Orin processor features (unknown architectural extension 'flagm')

Autonomous Machines Jetson & Embedded Systems Jetson AGX Orin
1

Hi, all.
I have a question about utilizing CPU features on Jetson AGX Orin.

My development environment is as follows:

  • Jetson AGX Orin Development Kit(32GB)
  • Flashed with the lastest Jetpack release r35.4.1

The problem occurs when I tried to compile my source code using gcc-11 with -march=native compile option. I know that official supported gcc version stays on 9, but I need to build a project which contains c++20 features.

While building my project, compilation errors printed as below:

[build] Assembler messages:
[build] Error: unknown architectural extension 'flagm'
[build] Error: unrecognized option -march=armv8.2-a+crypto+fp16+rcpc+dotprod+flagm

I have never experienced until the -march=native option is given, so started to investigate which compile options are provided via the keyword native for both gcc-9 and gcc-11.

$ /usr/bin/gcc-11 -Q -march=native --help=target
The following options are target specific:
  -mabi=                                lp64
  -march=                               armv8.2-a+crypto+fp16+rcpc+dotprod+flagm
  -mbig-endian                          [disabled]
  -mbionic                              [disabled]
...
Assembler messages:
Error: unknown architectural extension 'flagm'
Error: unrecognized option -march=armv8.2-a+crypto+fp16+rcpc+dotprod+flagm

$ /usr/bin/gcc-9 -Q -march=native --help=target
The following options are target specific:
  -mabi=                                lp64
  -march=                               armv8-a
  -mbig-endian                          [disabled]
  -mbionic                              [disabled]
...
(no error messages)

The output messages indicate that error generated from the compile option flagm that came from cpu features. As far as I know, gcc-9 does not support cortex A87ae(I found this information at here) optimization options while gcc-11 has optimization features for my Jetson device.
It seems to be gcc-11 found all the cpu features and get them into native. (I am not familiar with this level, so it might be wrong guess). The features are listed like,

$ cat /proc/cpuinfo 
processor       : 0
model name      : ARMv8 Processor rev 1 (v8l)
BogoMIPS        : 62.50
Features        : fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp uscat ilrcpc flagm
CPU implementer : 0x41
CPU architecture: 8
CPU variant     : 0x0
CPU part        : 0xd42
CPU revision    : 1
...

Also, I was able to find this flagm instruction on official Arm document. For my understanding, the project should be built since the compiler supports optimization options for Arm cortex a87ae.

I really cannot understand why gcc-11 complaining about flagm.
Any possible reasons?

3

Hi,
Please share the steps so that we can check and see if gcc 11 can be supported on 20.04. By default gcc version is

$ gcc --version
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

And do you know if it is gcc 11 in Ubunut 22.04?

4

Hi @DaneLLL

Here are the version output of gcc-9 and gcc-11 those I used.

$ /usr/bin/gcc-9 --version 
gcc-9 (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0 
Copyright (C) 2019 Free Software Foundation, Inc. 
This is free software; see the source for copying conditions. There is NO 
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ /usr/bin/gcc-11 --version 
gcc-11 (Ubuntu 11.4.0-2ubuntu1~20.04) 11.4.0 
Copyright (C) 2021 Free Software Foundation, Inc. 
This is free software; see the source for copying conditions. There is NO 
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

And yes, this is the same release version that Ubuntu 22.04 LTS uses as default.

5

Sorry for the possible confusion, the messages output above is from Jetpack r35.3.1.
I also tested on Jetpack r35.3.1 just now, but same behavior.

6

Hi,
This probably needs other users to share experience. Looks like gcc-11 is not installed in default release:

$ ls /usr/bin/gcc*
/usr/bin/gcc    /usr/bin/gcc-ar    /usr/bin/gcc-nm    /usr/bin/gcc-ranlib
/usr/bin/gcc-8  /usr/bin/gcc-ar-8  /usr/bin/gcc-nm-8  /usr/bin/gcc-ranlib-8
/usr/bin/gcc-9  /usr/bin/gcc-ar-9  /usr/bin/gcc-nm-9  /usr/bin/gcc-ranlib-9

It may not be well supported if you install it manually. Would see if other users have tried gcc-11 and can share experience.