On Thu, May 26, 2011 at 08:09:31PM +0200, Andi Kleen wrote: > On Thu, May 26, 2011 at 01:44:47PM -0400, Vivek Goyal wrote: > > On Thu, May 26, 2011 at 10:53:05PM +0530, K.Prasad wrote: > > > > > > slimdump: Capture slimdump for fatal MCE generated crashes > > > > > > System crashes resulting from fatal hardware errors (such as MCE) don't need > > > all the contents from crashing-kernel's memory. Generate a new 'slimdump' that > > > retains only essential information while discarding the old memory. > > > > > > > Why to enforce zeroing out of rest of the vmcore data in kernel. Why not > > leave it to user space. > > I think it's a good default to not do a full dump on MCE. > It's very unlikely to be useful for anything, and will just waste > reboot time (aka nines). If we are just extracting and saving MCE registers from vmcore, then reboot time does not increase. It increases only if user decides to extract and save extra data from vmcore. > > That said including the dmesg too may be a good idea. dmesg is already part of vmcore and user space tools can easily find it. I can easily imagine a default policy of a distro in user space where in case of MCE crash, we just extract dmesg and MCE registers (from vmcore notes section) reboot. This will be fast and will reduce the amount of code in kernel. IMHO, we should not introduce any additional notion of slimdump as such in kernel. A better thing would be to just read MCE registers and export to user space through ELF notes and then let user space automate the rest of it. Thanks Vivek
