* H. Peter Anvin [off-list ref] wrote:

There are some test drivers which really want /dev/mem to work.

Test drivers and test hardware with zero enumeration can use below 4G 
addresses just fine.

Also, debugging is not an issue and some non-default kernel or boot 
option can enable any sort of device i guess, so my main worry isnt 
really security but that we should stand in the way of the apparent 
practice of *shipping* user-space drivers that use /dev/mem ...

Thanks,

	Ingo