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Description of problem: RHEL6 kernel supports 'crashkernel=auto' boot parameter for kdump scripts. MRG Realtime 2.6.33-based kernel does not support the 'auto' value for crashkernel, but needs to to remain RHEL6 compatible.
*** Bug 710134 has been marked as a duplicate of this bug. ***
One note: the crashkernel=auto code was backported from RHEL6 and we kept the same behavior: for systems with less than 4GB of RAM the crashkernel memory is 0KB. Maybe we need to mention in the Release Notes that we are keeping RHEL6 behavior.
This change has been added to kernel-rt-2.6.33.9-rt31.70.el6rt patch queue.
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: Cause: mrg rt kernel doesn't know how to interpret the value 'auto' for the parameter 'crashkernel', translating it to 'crashkernel=0' Consequence: kdump is disabled as no memory is reserved for the kdump kernel. Fix: implement the 'crashkernel=auto' routines in the kernel. Result: Following the RHEL6 policy, if the machine has more than 4G of RAM installed, the kernel will reserve the necessary amount of memory to the kdump kernel whenever 'crashkernel=auto' is found in the kernel boot command line.
[root@mrg39 ~]# uname -r 2.6.33.9-rt31.73.el6rt.x86_64 [root@mrg39 ~]# rt-setup-kdump Not performing changes to /etc/grub.conf [root@mrg39 ~]# grep crashkernel= /etc/grub.conf kernel /vmlinuz-2.6.33.9-rt31.73.el6rt.x86_64[...snip...] crashkernel=auto kernel /vmlinuz-2.6.32-131.0.15.el6.x86_64[...snip...] crashkernel=auto [root@mrg39 ~]# cat /proc/cmdline ro [...snip...] crashkernel=auto [root@mrg39 ~]# service kdump start No kdump initial ramdisk found.[WARNING] Rebuilding /boot/initrd-2.6.32-131.0.15.el6.x86_64kdump.img No module ehci-hcd found for kernel 2.6.32-131.0.15.el6.x86_64, aborting. Failed to run mkdumprd [root@mrg39 ~]# locate ehci-hcd.ko /lib/modules/2.6.33.9-rt31.73.el6rt.x86_64/kernel/drivers/usb/host/ehci-hcd.ko [root@mrg39 ~]# The 2.6.33.9-rt31.73 kernel now accepts crashkernel=auto, however, it is not possible to prepare the kdump kernel. This seems to be related to that the EHCI HCD driver is built into the RHEL6 kernel, while RT kernel has it as a module. [root@mrg39 ~]# grep USB_EHCI_HCD /boot/config-2.6.3* /boot/config-2.6.32-131.0.15.el6.x86_64:CONFIG_USB_EHCI_HCD=y /boot/config-2.6.33.9-rt31.73.el6rt.x86_64:CONFIG_USB_EHCI_HCD=m -> ASSIGNED
This issue now found is not directly related to crashkernel=auto, however the crashkernel fix revealed another issue in the needed scripts for kdump. For now we will keep this bz open. A new bz covering the issue found will depend on this bz.