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Fixed

LIN1021-2686 : Using ramoops ftrace hangs the system

Created: Feb 2, 2022    Updated: Mar 28, 2022
Resolved Date: Mar 8, 2022
Found In Version: 10.21.20.8
Fix Version: 10.21.20.11
Severity: Standard
Applicable for: Wind River Linux LTS 21
Component/s: Kernel

Description

configure a project with BSP marvell-cn96xx;
configure the kernel to have CONFIG_PSTORE_FTRACE=y and CONFIG_PSTORE_RAM=y, or use the attached kernel configuration;
build a wrlinux standard image;
boot the board with above images;
check that ramoops is enabled and initialized:
root@marvell-cn96xx:~# dmesg | grep -i ramoops
[ 0.646246] printk: console [ramoops-1] enabled
[ 0.646392] pstore: Registered ramoops as persistent store backend
[ 0.646407] ramoops: using 0x3ff0000@0x1fc000000, ecc: 0
run the test command:
echo 1 > /sys/kernel/debug/pstore/record_ftrace
At this point the board will be unresponsive

Steps to Reproduce

To reproduce on VLM target 29153:
- configure a project with BSP marvell-cn96xx;
- configure the kernel to have CONFIG_PSTORE_FTRACE=y and CONFIG_PSTORE_RAM=y, or use the attached kernel configuration; 
- build a wrlinux standard image;
- boot the board with above images;
- check that ramoops is enabled and initialized:
root@marvell-cn96xx:~# dmesg | grep -i ramoops
[    0.646246] printk: console [ramoops-1] enabled
[    0.646392] pstore: Registered ramoops as persistent store backend
[    0.646407] ramoops: using 0x3ff0000@0x1fc000000, ecc: 0
- run the test command:
echo 1 > /sys/kernel/debug/pstore/record_ftrace
At this point the board will be unresponsive

To reproduce the issue on a different board, please see the documentation link from above; to put it shortly, one would have to define the DTS binding for the buffer or change the kernel cmdline accordingly.
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