On Fri, 2012-04-20 at 09:51 -0400, Vivek Goyal wrote: > On Thu, Apr 19, 2012 at 10:59:17AM +0200, Harald Hoyer wrote: > > Am 19.04.2012 00:28, schrieb Vivek Goyal: > > > Hi, > > > > > > I am trying to dump kernel vmcore to an software iscsi target (kdump). > > > kdump specifies the dump destination using "--mount" option. But dracut > > > does not even include the "iscsi" module and associated device is not > > > mounted in second kernel. > > > > > > Following is the dracut command line as called by /sbin/mkdumprd. > > > > > > dracut -m kdumpbase --add dash --add fstab-sys --add kernel-modules -c /dev/null -I /sbin/makedumpfile --mount '/dev/mapper/vg-lv_root / ext4 rw,seclabel,relatime,user_xattr,barrier=1,data=ordered' --mount '/dev/mapper/mpatha /mnt/common ext4 rw,seclabel,relatime,user_xattr,barrier=1,stripe=16,data=ordered' -M -f /boot/initramfs-3.3.2-1.fc17.x86_64kdump.img 3.3.2-1.fc17.x86_64 > > > > "-m kdumpbase" - This tells dracut to only use the kdumpbase dracut module > > So, because the iscsi dracut module is not added, dracut does not even check() it. > > > > Why is it "-m kdumpbase" and not "--add kdumpbase" ??? > > I don't know why -m is being used instead of --add. I tried changing it > to --add and uncompressed initramfs size changed from 36MB to 72MB. > > To me 32MB size itself is big. IIRc, in RHEL6 using our own mkinitrd, we had > uncomressed initrd size close to 25MB. > > In kdump environment we work in very restricted memory conditions. > Currently we reserve 128MB and there are calls to reduce it further. This > 128MB should load kernel, initramfs and run all the tools in initramfs > to actually save the vmcore to the target. > > So we need to figure out how can we reduce the size of initramfs for > kdump case. In the next mail I will add the output of --debug both for > -m kdumpbase and --add kdumpbase. > > From kdump perspective, we only need to mount targets as specified by > --mount option. We might not want to mount even root and it depends on > kdump.conf. If root is needed, we will pass that too on command line > using --mount. So this is little different from -H option. > > Can we modify dracut in such a way so that it packs only those modules > need to mount targets as specified --mount options? Yeah, I noticed this too, I think this is due to the dracut module "kernel-modules" includes more than enough kernel modules into initramfs, thus the size increased so much. Harald, if you have any idea to improve this? We need to find a way to tell "kernel-modules" module to only include the ones we want. Thanks. -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
