Hi, this is a followup question, but since it doesnt really fit the last topic, I started a new question.
I am trying to restart the Linux kernel without interrupting the safety critical app on the M4. Watchdogs and Resets on the iMX7 reset the whole SoC so now I am trying to reboot via kexec as suggested in SW reset via SRC_A7RCR0 - Technical Support - Toradex Community
But the reboot will hang while booting the new kernal after some odd seconds, if the M4 is not running, and won’t even start to boot after shutdown, if there is an App running in the M4.
To repoduce the issue I will describe what I have done.
I used the content of /proc/cmdline for *--append*. So Kernel command line will be no different to normal boot.
root@colibri-imx7-emmc:~# kexec
--load /media/mmcblk0p1/zImage
--type=zImage
--dtb=/media/mmcblk0p1/imx7d-colibri-emmc-eval-v3.dtb
--append='ip=off root=/dev/mmcblk0p2 ro
rootfstype=ext4 rootwait console=tty1 console=ttymxc0,115200n8 consoleblank=0
video=mxsfb:640x480M-16@60'
Followed by kexec -e, which shuts down the current kernel.
After the shutdown things started to differ, yielding two different results, depending on whether we started the Auxiliary M4 Core or not:
**with M4 running:** freeze after successful shutdownkexec_core: Starting new kernel
Disabling non-boot CPUs ...
CPU1: shutdown
Bye!
without M4 running: freeze immediately at different outputs at around 1.9 seconds
[ 1.921539] nf_tables: (c) 2007-2009 Patrick McHardy <kaber@trash.net>
[ 1.921792] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 1.922322] NET: Registered protocol family 10
[ 1.923240] ip6_tables: (C) 2000-2006 Netfilter Core Team
NOTE: it doesn’t freeze at the same output everytime, but always at around 1.92 seconds
One warning occurred:
[ 0.103000] ------------[ cut here ]------------
[ 0.103037] WARNING: CPU: 0 PID: 1 at /kernel-source//arch/arm/mm/ioremap.c:303
__arm_ioremap_pfn_caller+0xd8/0x1b4
[ 0.103070] Modules linked in:
[ 0.103097] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.166-2.8.6+g011d796 #6
[ 0.103127] Hardware name: Freescale i.MX7 Dual (Device Tree)
[ 0.103167] [<8010e6ac>] (unwind_backtrace) from [<8010ade0>] (show_stack+0x10/0x14)
[ 0.103207] [<8010ade0>] (show_stack) from [<8041094c>] (dump_stack+0x88/0x9c)
[ 0.103247] [<8041094c>] (dump_stack) from [<801240b0>] (__warn+0xe8/0x100)
[ 0.103276] [<801240b0>] (__warn) from [<80124178>] (warn_slowpath_null+0x20/0x28)
[ 0.103314] [<80124178>] (warn_slowpath_null) from [<801148dc>]
(__arm_ioremap_pfn_caller+0xd8/0x1b4)
[ 0.103353] [<801148dc>] (__arm_ioremap_pfn_caller) from [<80114a04>]
(__arm_ioremap_caller+0x4c/0x54)
[ 0.103394] [<80114a04>] (__arm_ioremap_caller) from [<80610424>](imx_rpmsg_find_vqs+0xc0/0x218)
[ 0.103434] [<80610424>] (imx_rpmsg_find_vqs) from [<8060fe90>] (rpmsg_probe+0xb4/0x420)
[ 0.103473] [<8060fe90>] (rpmsg_probe) from [<8047e274>] (virtio_dev_probe+0x204/0x2e4)
[ 0.103514] [<8047e274>] (virtio_dev_probe) from [<804b49ec>] (driver_probe_device+0x1e8/0x2b4)
[ 0.103553] [<804b49ec>] (driver_probe_device) from [<804b2fc4>] (bus_for_each_drv+0x44/0x94)
[ 0.103592] [<804b2fc4>] (bus_for_each_drv) from [<804b4724>] (__device_attach+0xb0/0x114)
[ 0.103630] [<804b4724>] (__device_attach) from [<804b3dbc>] (bus_probe_device+0x84/0x8c)
[ 0.103667] [<804b3dbc>] (bus_probe_device) from [<804b20ec>] (device_add+0x3ac/0x59c)
[ 0.103705] [<804b20ec>] (device_add) from [<8047def0>] (register_virtio_device+0xdc/0xf8)
[ 0.103743] [<8047def0>] (register_virtio_device) from [<80610a40>] (imx_rpmsg_probe+0x368/0x4b0)
[ 0.103783] [<80610a40>] (imx_rpmsg_probe) from [<804b62e0>] (platform_drv_probe+0x50/0xac)
[ 0.103823] [<804b62e0>] (platform_drv_probe) from [<804b49ec>] (driver_probe_device+0x1e8/0x2b4)
[ 0.103861] [<804b49ec>] (driver_probe_device) from [<804b4b5c>] (__driver_attach+0xa4/0xa8)
[ 0.103899] [<804b4b5c>] (__driver_attach) from [<804b2f1c>] (bus_for_each_dev+0x4c/0x9c)
[ 0.103937] [<804b2f1c>] (bus_for_each_dev) from [<804b405c>] (bus_add_driver+0x188/0x20c)
[ 0.103975] [<804b405c>] (bus_add_driver) from [<804b5408>] (driver_register+0x78/0xf4)
[ 0.104014] [<804b5408>] (driver_register) from [<80b2c70c>] (imx_rpmsg_init+0x14/0x34)
[ 0.104052] [<80b2c70c>] (imx_rpmsg_init) from [<80101790>] (do_one_initcall+0x44/0x170)
[ 0.104092] [<80101790>] (do_one_initcall) from [<80b00d90>] (kernel_init_freeable+0x15c/0x1e8)
[ 0.104133] [<80b00d90>] (kernel_init_freeable) from [<807a7af8>] (kernel_init+0x8/0x110)
[ 0.104172] [<807a7af8>] (kernel_init) from [<80107650>] (ret_from_fork+0x14/0x24)
[ 0.104212] ---[ end trace ea35a24a4a549cbe ]---
Any suggestions what might cause the different behaviours and how one might avoid the freezes?