utcb as a shared page instead of the message registers.
Implemented the code that passes task information from mm0 to fs0
using the fs0 utcb. The code seems to work OK but:
There's an issue with anon pages that they end up on the same swapfile
and with same file offsets (e.g. utcb and stack at offset 0). Need to
fix this issue but otherwise this implementation seems to work.
TODO:
- Separate anon regions into separate vmfiles.
- Possibly map the stacks from virtual files so that they can be
read from userspace in the future for debugging.
- Possibly utcb could be created as a shared memory object using shmget/shmat
during startup.
This will help when syscalls have long arguments individual
utcbs can be mapped to server tasks and kept mapped in until the
tasks die, as opposed to map requests every time a server task maps
a different utcb at the same virtual address.
The changes have preparation code to also passing the utcb info
through the stack as part of the environment.
To sum up env and arg regions have also been added above the stack and
env region is to be used to pass on the utcb address information at
task startup.
Headers 3 headers related to message registers and utcbs are now merged under
utcb.h in libl4. Some message register definitions used by the kernel are now
moved into kernel's glue/message.h. This avoids the duplication of same
definitions. Also the total number of mregs are now determined by arch-specific
kernel header, which is good.
