Issue with ext4

[workonlinux]

I have a Centos 6.3 virtual box built with kernel 2.6.32.
The primary issue is that I want to debug ext4 module.

Now I got the Rpm stuff etc; prepared a DEBUG custom kernel build and a module build for ext4(made it as a loadable module in menuconfig). Installed everything and I booted from this new kernel. I tried to debug the same from a host by using the recently built vmlinux and ext4.ko and loaded the symbol file. But the debugger does not break at any ext4 function which I intend to.

My guess is that since the Centos has default ext4 enabled, even for custom kernel it is not allowing me to debug it because I have to do a insert module(insmod ext4.ko). So I tried that as well; but it says error - in use. Again reason may be that the root partition itself uses it so I cannot unload it also. So its like a chicken and egg problem.

I tried lot of other stuffs but unfortunately none seem to work.
Can somebody please suggest me (1) how to insert ext4 exactly (2) if that is not needed, then atleast I want to debug the ext4.

Sincere thanks in advance.

[Irithori]

Never debugged ext4.
But if you want to load/unload the ext4 kernelmodule, you could install your centos system with xfs only.
Grub can read xfs just like ext2/3/4, so it should boot.

Just leave a bit of space on your harddisc for a ext4 testpartition.

[workonlinux]

thanks a lot for the suggestion.
So just to understand(from my side), it means I will build a centos system with xfs only. But I tried to install Centos 6.3 with the iso.
So even with the "Create Custom Layout" in the Centos Installer, I do not see the option of XFS in the dropdown menu for the partition that I'm trying to.

Am I doing anything wrong here ?

[Irithori]

It is there.
Last in the dropdown menu.
You can choose "format as" ext2/3/4, lvm, raid, swap and then xfs.

[workonlinux]

Hi,

sorry to repeat it again, but please help me understand if I'm doing something wrong -

I'm using the CentOS-6.3-x86_64-LiveCD.iso. So once I boot the same and install it and then try creating "Custom layout", I see only these options - ext2,ext3,ext4,lvm,raid,swap and vfat.
So basically I can see all the options listed by you except the xfs.

Thanks a lot

[Irithori]

Hmm, with the CentOS-6.3-x86_64-bin-DVD1.iso xfs is definitely there.
I am just downloading CentOS-6.3-x86_64-minimal.iso and CentOS-6.3-x86_64-netinstall.iso to see if xfs is an option there.

[Irithori]

Oki, it seems only an installation via CentOS-6.3-x86_64-bin-DVD1.iso offers xfs.
Which is a bit strange, as it seems a) fundamental and b) the xfs rpms are not big.

[workonlinux]

oh ok. thanks for the info.
I will try downloading CentOS-6.3-x86_64-bin-DVD1.iso. But again CentOS-6.3-x86_64-bin-DVD2.iso will also be needed mostly I suppose as a part of installation.

[Irithori]

Whether or not the second iso is needed depends on the package groups you choose for the initial install.
A server only install without gui will only need the first.

[workonlinux]

Well, now I was able to see the same. But unfortunately even this DVD iso does not allow xfs root partition
It says - Bootable partitions cannot be on an xfs file system.

This was the similar problem when I tried to make it ext3 as boot.