kernel comparison
#4
Hello eard5849,
(07-10-2019, 05:49 AM)beard5849 Wrote: Me, an aarch64 development system on which I can test the NEON extended instructions.
So, I want to see "neon" in /proc/cpuinfo
see  bellow the links to ARM documentation..
Its related to NEON in ARMv7-A and ARMv7-R,
But maybe same behaviour( even though that there are changes between ARMv7 and ARMv8 )..

Sections 2.1.8 and 2.1.9:
NEON

Quote:A stock kernel is the kernel released by Linux at www.kernel.org, without modification.

If you use a Linux stock kernel to run your application, there is no need to manually enable the NEON unit.
The kernel automatically enables the NEON unit when it encounters the first NEON instruction.

If the NEON unit is disabled and the application tries to execute a NEON instruction, it throws an Undefined Instruction exception.

The kernel uses this exception to enable the NEON unit and then executes the NEON instruction.

The NEON unit remains enabled until there is a context switch.
When a context switch is required, the kernel might disable the NEON unit to save time and power.


Verify:
Code:
root@rockpro64:~# zcat /proc/config.gz | grep NEON
CONFIG_KERNEL_MODE_NEON=y

(07-10-2019, 05:49 AM)beard5849 Wrote: Also since the RK3399 has six cores, 4x A53 and 2x A72, I want to see that in /proc/cpuinfo.


I see that in '/proc/cpuinfo'
Code:
root@rockpro64:~# cat /proc/cpuinfo
processor : 0
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4

processor : 1
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4

processor : 2
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4

processor : 3
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 4

processor : 4
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 2

processor : 5
BogoMIPS : 48.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 2

Serial : 0000000000000000

root@rockpro64:~# pwd
/root
root@rockpro64:~# git clone --branch master https://github.com/tuxd3v/tools.git && cd tools
Cloning into 'tools'...
remote: Enumerating objects: 44, done.
remote: Counting objects: 100% (44/44), done.
remote: Compressing objects: 100% (34/34), done.
remote: Total 44 (delta 10), reused 42 (delta 8), pack-reused 0
Unpacking objects: 100% (44/44), done.
root@rockpro64:~/tools# ./aarch mtune

cortex-a72.cortex-a53

It is reported correctly

Regards,
tux


Messages In This Thread
kernel comparison - by Mentaluproar - 07-01-2019, 02:29 AM
RE: kernel comparison - by mknawabi - 07-09-2019, 09:21 PM
RE: kernel comparison - by beard5849 - 07-10-2019, 05:49 AM
RE: kernel comparison - by tuxd3v - 07-29-2019, 07:30 PM

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