On Thu, 2006-12-14 at 10:10 +0530, Vivek Goyal wrote: > On Thu, Dec 14, 2006 at 11:41:55AM +1000, Bradley Schatz wrote: > > Hi Vivek, Eric and Hari, > > > > Sorry to mass mail you all - it wasnt clear what the best forum to talk > > about kdump is. > > Hi Bradley, > > You can do discussion regarding kdump on fastboot mailing list. Copying > this thread to mailing list. > > > > > I read a thread in LKML recently discussing kdump and quiescing devices such > > as networking cards on bootup of the kdump kernel. > > > > What changes did you end up implementing to take care of this? > > > > So far we have been fixing individual drivers. Basically harden the drivers > to be able to initialize in a hostile environment where underlying device > might be in unknown state. We have introduced a kernel command line > parameter "reset_devices" and device drivers can make use of this > parameter to determine that they are initializing in a potentially hostile > environment and they need to first try to reset the device and then > go ahead with rest of the initialization.
Even though I agree with the philosophy that drivers should be able to initialize devices in potentially hostile environment (and "reset_device" should ultimately become unnecessary), there is still some need to quiesce the devices before kexec'ing a new kernel. We are already seeing problems with in-flight DMAs from non-quiesced devices when a hardware I/O TLB is involved. It just makes me nervous to attempt kexec a new kernel not knowing the system has quiet down. At the very least, we should turn bus mastering off on all PCI devices to disable any DMAs from them before we attempt kexec. -- Khalid > > I need to put a small patch in kexec-tools to pass this parameter to > kdump kernel. > > Fixing individual drivers is a long painful process. Still haven't found > any generic scheme to solve the problem. > > Thanks > Vivek > _______________________________________________ > fastboot mailing list > [email protected] > https://lists.osdl.org/mailman/listinfo/fastboot -- ==================================================================== Khalid Aziz Open Source and Linux Organization (970)898-9214 Hewlett-Packard [EMAIL PROTECTED] Fort Collins, CO "The Linux kernel is subject to relentless development" - Alessandro Rubini _______________________________________________ fastboot mailing list [email protected] https://lists.osdl.org/mailman/listinfo/fastboot
