On Thu, May 30, 2019 at 6:36 AM Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: > > > Suganath, > > > This configuration should reset during driver unload or shutdown to > > the default settings. For this driver takes copy of default ioc page 1 > > and copy backs the default or unmodified ioc page1 during unload and > > shutdown. so that on next driver load (e.g. if older version driver is > > loaded by user), current modified changes on ioc page1 won't take > > effect. > > What happens if the system crashes before the old page is put back? Any changes done on the pages from 'current region' will persist until HBA firmware is alive. if diag reset happens or cold boot/reboot occurs then firmware will get reinitialize and it will overwrite current region pages with NVRAM region pages. So the changes done on the 'current region' will be erased. Now when system crashes, kdump utility will trigger a warm reboot into kdump kernel. when mpt3sas driver getting loaded then it observes that HBA is in OPERATIONAL state. So it issues the diag reset to move the HBA state to READY state and hence the changes made in the 'current region' will be erased. After memory is dumped into the pre-configured location, kdump utility will do cold reboot to boot in to standard kernel. As cold reboot occurs HBA firmware will initialize from day one and if any changes done on 'current region' will overwrite with NVRAM region. In normal warm reboot case, driver issues the Message Unit Reset (to move HBA state to READY state) from shutdown callback before going for reboot operation and hence in this case driver has to copy back the default settings. Thanks, Sreekanth > > -- > Martin K. Petersen Oracle Linux Engineering
