We have an IMX6Q platform on which we encounter a very strange issue.
While rebooting the system, platform hangs @ flush_pmd_entry(pmd). This is probably because one of the CPUs ends up crashing and won't restart. Don't have a debugger to check the actual state of the machine.
root@android:/ # reboot
[ 15.914484] SysRq : Emergency Remount R/O
[ 15.930771] EXT4-fs (mmcblk0p6): re-mounted. Opts: (null)
[ 15.949119] EXT4-fs (mmcblk0p5): re-mounted. Opts: (null)
[ 15.963710] EXT4-fs (mmcblk0p7): re-mounted. Opts: (null)
[ 15.969570] Emergency Remount complete
[ 16.022363] imx2-wdt imx2-wdt.0: Device shutdown: Expect reboot!
[ 16.028632] Restarting system.
Mention: using fsl kernel 3.0.35
The exact asm line where system hangs is (tlbflush.h):
<><-->asm("mcr<-->p15, 0, %0, c7, c10, 1<>@ flush_pmd"
<><--><-->: : "r" (pmd) : "cc");