I've been getting this horribly annoying kernel panic in X recently, so I decided to use kdump/kexec to try and get at my vmcore.

I've set up kexec as per the instructions in /Documentation/kdump/kdump.txt

I've enabled sysrq in both the kernel, AND, in the /etc/sysctl.conf

The system responds to sysrq-C when I'm in the console and before startx, which properly loads the dump kernel and I can get access to my /proc/vmcore

However, when I'm in X (after startx), sysrq-c does NOT load up the crash kernel, and INSTEAD responds by hanging my system (NO blinking capslock though).

I'm on a Intel Core 2 Duo, 64-bit, 2GB of memory, NVIDIA QUADRO FX 570M, and note that my CONFIG_PHYSICAL_START is 0x200000, NOT 0x100000, (I wasn't sure if this should be changed as the default was 0x200000). But this shouldn't matter because the kernel is RELOCATABLE(=y)

I've attached my:

.config : http://dpaste.com/105844/
lspci : http://dpaste.com/105846/
lsmod : http://dpaste.com/105848/
dmesg : http://dpaste.com/105849/
grub.conf : http://dpaste.com/105850/

my kexec command is "sudo kexec -p /usr/src/linux-2.6.28-gentoo/arch/x86/boot/bzImage --append=root=/dev/sda3 1 irqpoll maxcpus=1 reset_devices"


Please help.

Hi,

Are you still facing the same issue? I also faced similar issue but working around with the values of crashkernel=x@y solved my issue.

Now I am facing issues in reading the /proc/vmcore ... /dev/oldmem.
Can you please share how to read the memory using /proc/vmcore interface?

or any application program?

Like if I want to read a perticual page fram number etc.

Moreover, if you have any idea regarding reading data to 32 bit user space from 64 bit kernel space.

Chandan,

How did you resolve the issues with the crashkernel setting? I am currently having an issue with that myself but havent been able to resolve them. I have set crashkernel=128M@64M in my grub.conf file but kdump still complains it hasnt been set when restarting kdump.

hi,

Please make sure that you have set kexec in your .config file.

CONFIG_KEXEC=y
CONFIG_CRASH_DUMP=y
CONFIG_PHYSICAL_START=0x200000
CONFIG_RELOCATABLE=y
CONFIG_PHYSICAL_ALIGN=0x200000

and then remember to pass crashkernl=Y@X into your primary kernel. Moreover, please check the .config file of the kdum in /etc.

Currently I am facing issues with generating the /proc/vmcore file. Its getting generated but of zero size. and working on it.

Hope it helps.

Dhanyawad