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Virtualbox + kgdb: Losing symbol information

Posted by krkhan 
Virtualbox + kgdb: Losing symbol information
June 14, 2017 07:48PM
I have an Ubuntu 16.04 VM running in Virtualbox.

I'm building kernel from git using make deb-pkg.

After I install all the deb packages (including debug symbols) on the VM and restart it, I can see in uname -r output that the appropriate kernel was booted from.

I'm passing the following parameters to the kernel:

kgdboc=ttyS0,115200 kgdbwait

Once the kernel boots, I am able to connect to it via socat + gdb from host.

I'm using the full uncompressed vmlinux file to start the gdb which contains all the debugging symbols.

However, I can't see any of the symbols in backtrace etc.

$ du -sh vmlinux
425M	vmlinux
$ gdb vmlinux 
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later [gnu.org]
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from vmlinux...done.
(gdb) target remote /dev/pts/2
Remote debugging using /dev/pts/2
0xffffffffb113c5b4 in ?? ()
(gdb) bt
#0  0xffffffffb113c5b4 in ?? ()
#1  0xffffb035421c7dd0 in ?? ()
#2  0xffffffffb113c60c in ?? ()
#3  0xffffb035421c7e00 in ?? ()
#4  0xffffffffb153035a in ?? ()
#5  0x0000000000000002 in irq_stack_union ()
#6  0x00000000013a7408 in ?? ()
#7  0xffff8fb8bd0d3b00 in ?? ()
#8  0xffffb035421c7e18 in ?? ()
#9  0xffffffffb15307df in ?? ()
#10 0xffff8fb8b8779900 in ?? ()
#11 0xffffb035421c7e38 in ?? ()
#12 0xffffffffb12ab412 in ?? ()
#13 0xffff8fb8bd0d3b00 in ?? ()

Any ideas what am I doing wrong?

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