On Thu, Nov 15, 2012 at 01:55:51AM +0900, Joonsoo Kim wrote:

In current implementation, we used ARM-specific flag, that is,
VM_ARM_STATIC_MAPPING, for distinguishing ARM specific static mapped area.
The purpose of static mapped area is to re-use static mapped area when
entire physical address range of the ioremap request can be covered
by this area.

This implementation causes needless overhead for some cases.

In what cases?

We unnecessarily iterate vmlist for finding matched area even if there
is no static mapped area. And if there are some static mapped areas,
iterating whole vmlist is not preferable.

Why not?  Please put some explanation into your message rather than
just statements making unexplained assertions.

Another reason for doing this work is for removing architecture dependency
on vmalloc layer. I think that vmlist and vmlist_lock is internal data
structure for vmalloc layer. Some codes for debugging and stat inevitably
use vmlist and vmlist_lock. But it is preferable that they are used outside
of vmalloc.c as least as possible.

The vmalloc layer is also made available for ioremap use, and it is
intended that architectures hook into this for ioremap support.