------- Comment From gowrishankar.m.com 2009-08-27 22:15 EDT-------
From /proc/iomem report, it seems portion of memory is not
reserved (under 00100000-cffbcdbf : System RAM) for Crash
kernel.

------- Comment From sripathik.com 2009-10-19 08:48 EDT-------
We hit the same problem with debug kernel as well. Looks like recent kernels have gotten bigger and hence can't load the kdump kernel at low addresses. Debug kernel can't load crash kernel even at 32M. It needs to load at 48M. There is a message during bootup:

[root@elm9m98 ~]# dmesg |grep -i crashkernel
Command line: root=/dev/sda3 crashkernel=128M@32M console=tty1
console=ttyS1,19200
crashkernel reservation failed - memory is in use
Kernel command line: root=/dev/sda3 crashkernel=128M@32M console=tty1
console=ttyS1,19200

Since the kernel can figure out the offset by itself, one should not pass the offset while configuring kdump any more. I think RH should update http://rt.et.redhat.com/page/RHEL-RT_kdump/kexec and
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.1/html/Realtime_Tuning_Guide/sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-Using_kdump_and_kexec_with_the_RT_kernel.html
for MRG1.2.

------- Comment From sripathik.com 2009-10-19 08:49 EDT-------
*** Bug 55784 has been marked as a duplicate of this bug. ***

------- Comment From dvhltc.com 2009-11-02 17:06 EDT-------
Clark said he'll look into this and try to fix asap.

No longer dependent on bug #536926, as this bug is related towards the 2.6.31 kernel, and not the 2.6.24.7 kernel MRG-1.2 will ship.

This bug is not relevant for the MRG-1.2 release in the current phase.  But will be important when we do ship a newer base kernel.

investigating correctness of the rt-setup-kdump script wrt .33 kernel

------- Comment From gowrishankar.m.com 2010-05-02 07:32 EDT-------
I have verified with the current mrg 1.3 alpha packages.

[root@elm9m96 ~]# uname -a
Linux elm9m96 2.6.33.2-rt13.12.el5rt #1 SMP PREEMPT RT Fri Apr 9 07:28:20 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

[root@elm9m96 ~]# cat /proc/cmdline
root=/dev/sda3 console=ttyS1,19200 crashkernel=128M@16M

[root@elm9m96 ~]# /etc/init.d/kdump start
Starting kdump:                                            [FAILED]

Crash memory is still not reserved if offset is set as 16M, where as with 32M offset
kdump works.

[root@elm9m96 ~]# /etc/init.d/kdump status
Kdump is operational

[root@elm9m96 ~]# cat /proc/cmdline
root=/dev/sda3 console=ttyS1,19200 crashkernel=128M@32M

------- Comment From gowrishankar.m.com 2010-05-02 07:33 EDT-------
Used packages are:
[root@elm9m96 ~]# rpm -qa|grep rt-setup
rt-setup-1.6-3.el5rt

[root@elm9m96 ~]# rpm -qa|grep kdump
system-config-kdump-1.0.14-4.el5

------- Comment From dvhltc.com 2010-05-03 11:18 EDT-------
Clark is there a newer version of rt-setup we should be looking at?

------- Comment From gowrishankar.m.com 2010-05-26 14:01 EDT-------
(In reply to comment #16)
> Clark is there a newer version of rt-setup we should be looking at?

I am trying to understand the context of rt-setup-kdump. I played with
rt-setup-kdump (rt-setup-1.6-3.el5rt).

It just tries to update /etc/sysconfig/kdump and adds crashkernel entry
in /boot/grub/grub.conf (128M incase -v2 and 32M@128M in case of -v1).
So how is it going to address the offset issue of having 16M in our problem ?

------- Comment From dvhltc.com 2010-05-26 14:24 EDT-------
(In reply to comment #18)
> (In reply to comment #16)
> > Clark is there a newer version of rt-setup we should be looking at?
>
> I am trying to understand the context of rt-setup-kdump. I played with
>  rt-setup-kdump (rt-setup-1.6-3.el5rt).
>
> It just tries to update /etc/sysconfig/kdump and adds crashkernel entry
> in /boot/grub/grub.conf (128M incase -v2 and 32M@128M in case of -v1).
> So how is it going to address the offset issue of having 16M in our problem ?

My understanding is that the more recent kernels can autodetect where to reserve the memory for kdump. Explicitly setting it via the @16M or @32M can confuse things and cause failures. We expected that ensuring rt-setup specified only 128M and not 128M@XXM would resolve the problem.

------- Comment From gowrishankar.m.com 2010-05-31 06:36 EDT-------
I have verified rt-setup-kdump on rhel5.5 with both v1 and v2 kernels.
Crash kernel entries are added appropriately in grub.conf and kdump
works with them. I used rt-setup of version 1.6-3.el5rt .

------- Comment From amitarora.com 2010-05-31 07:35 EDT-------
Hello Redhat,

We have verified that the rt-setup-kdump works fine and we are able to get the dump with the newer kernels.

I hope there is a plan to make the required changes to the "Using kdump and kexec with the MRG Realtime kernel" section of the "Realtime Tuning Guide" for MRG 1.3 - with the release. If so, I will go ahead and close this bug. Please confirm.

For example, MRG1.2 has similar document at :
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.2/html/Realtime_Tuning_Guide/sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-Using_kdump_and_kexec_with_the_RT_kernel.html

which states:

" Open the /etc/grub.conf file in your preferred text editor and add a crashkernel line to the boot kernel. This line takes the form:

crashkernel=[MB of RAM to reserve]M@[memory location]M

A typical crashkernel line would reserve 128 megabytes (128M) at 16 megabytes (16M), which is equivalant to the address 0x1000000:

crashkernel=128M@16M
"

Now, this document for MRG 1.3 should not suggest "@[mempry location]"  option.

Thanks!

------- Comment From gowrishankar.m.ibm.com 2010-05-02 07:32 EDT-------







------- Comment From gowrishankar.m.ibm.com 2010-05-02 07:33 EDT-------



------- Comment From gowrishankar.m.ibm.com 2010-05-26 14:01 EDT-------





------- Comment From gowrishankar.m.ibm.com 2010-05-31 06:36 EDT-------