Kernel Mode Linux is a technology which enables
the execution of user programs in a kernel mode.
In Kernel Mode Linux, user programs can access
kernel address space directly. Unlike kernel
modules, user programs are executed as ordinary
processes (except for their privilege level), so
scheduling and paging are performed as usual.
Although it seems dangerous, the safety of the
kernel can be ensured through such methods as
static type checking, software fault isolation,
and so forth.