On Tue, Oct 13, 2015 at 05:24:31PM +0530, Mayuresh wrote: > On Sun, Oct 11, 2015 at 01:13:42PM -0400, Christos Zoulas wrote: > > | > This looks like a NULL pointer dereference. Do you have a backtrace? > > | > > | Unfortunately the keyboard stops working when db prompt appears. So cannot > > | gather complete trace. > > > > Compile a kernel with > > options DDB_ONPANIC 2 > > (man 4 options) > > Did just that, make depend and make. Copied the kernel to bootable USB and > tried to boot from it. Get the panic error but not stack trace.
On a healthy system I tried triggering ddb with above kernel (with DDB_ONPANIC set), with Ctrl-Alt-Esc. It did not print trace. To cross check that the option is effective I did this: $sysctl ddb.onpanic ddb.onpanic = 2 Also commented out the following line in /etc/sysctl.conf as below to ensure that it is not overriding the compiled option. #ddb.onpanic?=1 So looks like my procedure was alright. Is there anything else needed to make kernel print trace on entering ddb, when keyboard can't be used? Mayuresh.
