[linuxsh-shmedia-dev] Should CONFIG_HIGHMEM be defined?

[Gaster, B. <ben...@su...>]

Hello!
=20
It seems that for some ports of the Linux kernel RAM is mapped
completely into the kernel's address space while on machines with
"highmem" some memory is mapped into the kernel virtual memory
dynamically. The use of "highmem" seems to be controlled through the
configuration has define:
=20
CONFIG_HIGHMEM
=20
and defining this has the important consequence of adding the following
field to the definition of "struct page" in mm.h:
=20
void *virtual;      /* Kernel virtual address (NULL if not kmapped, ie.
highmem) */
=20
If we look in ./arch/shmedia/config.in  we see that CONFIG_HIGHMEM is
not defined and thus the virtual field is never defined. This seems to
imply that no memory can be mapped into the kernel dynamically! Can
anyone explain this in more detail as the problem is I'm porting some
code to SHMedia Linux that makes reference to this field.
=20
thanks,
=20
ben.