On 05/15/2013 02:05 AM, HATAYAMA Daisuke wrote: > Currently, read to /proc/vmcore is done by read_oldmem() that uses > ioremap/iounmap per a single page. For example, if memory is 1GB, > ioremap/iounmap is called (1GB / 4KB)-times, that is, 262144 > times. This causes big performance degradation. read_oldmem() is fundamentally broken and unsafe. It needs to be unified with the plain /dev/mem code and any missing functionality fixed instead of "let's just do a whole new driver". -hpa
