On Wed, Aug 1, 2018 at 10:55 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > 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. > Ok. But trace_printk output is available only after boot, so to debug any boot issues, it may not be helpful. And gdb for kernel debugging? Maybe u meant kgdb? Let me check if this issue is only for pstore path or not. -- 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
