On Wed, Aug 01, 2018 at 10:46:06PM +0530, Ivid Suvarna wrote: > On Wed, Aug 1, 2018 at 6:49 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On 08/01/2018 05:35 AM, Ivid Suvarna wrote: > >> > >> Hi, > >> > >> When pstore is enabled and a *pr_info(any printk) in > >> __memcpy_toio(arch/arm64/kernel/io.c)* is added, kernel wont boot and > >> just hangs. > >> > >> The path where __memcpy_toio is called is below: > >> > >> ->persistent_ram_update > >> -> memcpy_toio > >> -> __memcpy_toio > >> > >> I tried with trace_printk and kernel boots fine. I understand that > >> printk has overhead, but is this expected when we use some printk > >> statement in __memcpy_toio? > >> > > > > I think the problem may be that the printk() output is copied to pstore. > > Since pstore calls memcpy_toio(), you get a nice recursion if you add a > > printk() call to it. > > > > Is there any solution to this other than not adding printk :p Well, disabling pstore would help. You could also use a trace function, as you already found out, or you could use gdb for debugging. Since this is obviously a debug image, you should be willing to accept some limitations/restrictions. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
