On Mon, Jul 09, 2007 at 11:21:54AM +0200, Bernhard Walle wrote: > Hello, > > * Dan Aloni <da-x at monatomic.org> [2007-07-06 16:58]: > > > > Redhat has a makedumpinfo util which they intend to use as slim > > kernel-version-independent utility on kdump rootfs in order to > > save /proc/vmcore in a compact manner. > > I think you mean makedumpfile, don't you? Yes, a typo, sorry. > > A patch that I am working on will make it possible to integrate > > the output of 'makedumpinfo -g' into vmlinux as the final build > > stage of the kernel. This information will be presented itself > > as /proc/kcore.info for the first kernel throughout its entire > > execution. > > That sounds good. But I doubt that kernel developers like the idea of > needing another utility in the build process ... I don't think it would add much complexity to build process as it is now, just like the other tools that transparently do post-linking modifications. As far as the developer is concerned, there's just the vmlinux and/or bzImage files that get emitted at the end. > > Then inside initramfs of the first kernel, a small > > util will modify the vmlinux file of the kdump kernel before it > > gets loaded so that another special file appearing as > > /proc/vmcore.info under the kdump kernel will present the same > > info. > > Where do you get the info from? If you're in the kdump initrd, > then the kdump kernel is already loaded. Do you want to attach the > info from the crashed kernel to the initrd of the kdump kernel? Not exactly. Let me describe the procedure in greater detail. Basically, it would go like this: 1. <normal bootloader boot> 2. <normal initramfs> 3. embed_configfile /proc/kcore.info /vmlinux-kdump 4. kexec -l vmlinux-kdump <....> 5. <boot continues> 6. <crash> 7. <kdump kernel boot> 8. <kdump initramfs runs> 9. makedumpfile -i /proc/vmcore.info <....> NOTES: ** in step 3 embed_configfile modifies vmlinux-kdump in place, copying /proc/kcore.info into the data section of the vmlinux-kdump at certain symbol (e.g. 'char core_info[0x1000]'). ** in step 9 that data section variable (e.g. core_info) which was originally holds the content of /proc/kcore.info is being presented as /proc/vmcore.info for the util to use. To complete the picture, at the final build stage of vmlinux we would have this: makedumpfile -g vmlinux.configfile -x vmlinuxx embed_configfile vmlinux.configfile vmlinux rm vmlinux.configfile BTW I think there could be a confusion between makedumpfile's CONFIGFILE and the .config file, so we should pick a different name for it... -- Dan Aloni XIV LTD, http://www.xivstorage.com da-x (at) monatomic.org, dan (at) xiv.co.il
