Patent ID: 8640117

Claim:
A software update method comprising: performing, by an operation on an operating system (OS) in a normal mode, generating processing which includes call processing and is executed via a plurality of processes, the OS having the normal mode and a software update mode; restarting, by an operation on the OS in the normal mode, the OS in the software update mode for calling a verification processing when being called by the call processing; and performing, using a processor, the verification processing for verifying the generating processing when being called by the OS in the software update mode, wherein the generating processing further generates a plurality of check files indicating an execution status of the generating processing by the plurality of processes, wherein the verification processing verifies the plurality of check files generated by the plurality of processes when being called by the OS in the software update mode, wherein the generating processing of generating the check file stores time data including the time of the generation or data based on the time of the generation in each of the plurality of check files, wherein the verification processing verifies whether or not a difference between a present time and data having a largest value of the time data stored in each of the plurality of check files is smaller than a first threshold value, and validates the verification result if the difference is smaller than the first threshold value.