Access permissions of /dev/mem

I have a set of questions regarding /dev/mem:

1. Many articles on the net, seem to refer /dev/mem as the gateway to "Physical RAM". But if I am right, /dev/mem is the gateway to the "Physical Address Space" of the processor which might include control registers of many HW peripherals and not just the RAM? Please, correct me if I am wrong!

2. In order to prevent attackers from misusing /dev/mem and altering kernel memory, a flag CONFIG_STRICT_DEVMEM needs to be enabled which will prevent user apps from accessing physical address space beyond 1MB. I checked the config file on my PC (Ubuntu) and found that CONFIG_STRICT_DEVMEM = y. And I wrote a program which tries to read to physical memory beyond 1 MB and I was able to read! No segmentation fault or any Operation NOT Permitted error. How is this possible?

My program roughly looks like this:

fd = open ( "/dev/mem", O_RDWR);ptr = (int*) mmap(0, MAP_SIZE, PROT_READ, fd, myAddress & (~MAP_MASK));printf("%d", *ptr);