Use a bit allocator for the allocation management of thread contexts,
instead of holding allocation information within the Thread_base objects,
which lead to race conditions in the past.
Moreover, extend the Thread_base class interface with the ability to
to add additional stacks to a thread, and associate the context they're
located in with the corresponding Thread_base object. Additional stacks
can be used to do user-level scheduling with stack switching, without breaking
Genode's API.
Fixes#1024Fixes#1036
Currently, on the Arndale platform, core uses a different thread context
area base address than the other tasks (0x20000000 vs. 0x40000000). This
is problematic, because core calculates the location of the UTCB area of a
new thread relatively to core's own thread context area base. So, the UTCB
area of non-core threads ends up in a virtual address range which is
outside of the task's thread context area and not marked as used in the
task's RM session.
With this patch, the same thread context area base address gets used in
core and in the other tasks.
Fixes#779.
Make 'context_area_virtual_base' platform configurable. On Arndale, we
need to move the context area to a location that does not interfere with
the address range of physical memory.
This patch simplifies the way of how Genode's base libraries are
organized. Originally, the base API was implemented in the form of many
small libraries such as 'thread', 'env', 'server', etc. Most of them
used to consist of only a small number of files. Because those libraries
are incorporated in any build, the checking of their inter-dependencies
made the build process more verbose than desired. Also, the number of
libraries and their roles (core only, non-core only, shared by both core
and non-core) were not easy to capture.
Hereby, the base libraries have been reduced to the following few
libraries:
- startup.mk contains the startup code for normal Genode processes.
On some platform, core is able to use the library as well.
- base-common.mk contains the parts of the base library that are
identical by core and non-core processes.
- base.mk contains the complete base API implementation for non-core
processes
Consequently, the 'LIBS' declaration in 'target.mk' files becomes
simpler as well. In the most simple case, only the 'base' library must
be mentioned.
Fixes#18
