zephyr/doc/reference/usermode
Andrew Boie 4abc38b342 doc: usermode: stack access policy change
The current policy of always excluding stacks that aren't
owned by the current thread only works well on MPU systems,
where it is very fast to have a reserved MPU region corresponding
to the stack buffer of the current thread.

This unfortunately is not efficient on MMU-based systems, it
would require either a different set of page tables per thread
or an expensive page table update on context switch.

This PR relaxes the documented policy to leave it up to the
implementation whether threads that all belong to the same
memory domain can see each other's stacks.

There's lots of precedent for this, for example on Linux threads
in the same process can all access each other's stacks.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
2020-10-21 10:20:23 -07:00
..
auto_mem_domain.png
index.rst docs: fix user mode sidebar 2020-05-20 20:08:54 +02:00
kernelobjects.rst doc: Apply constant qualifier on device instance where relevant 2020-09-02 13:48:13 +02:00
memory_domain.rst doc: update struct references to use :c:struct: 2020-08-31 09:57:33 -04:00
mpu_stack_objects.rst global: Remove leading/trailing blank lines in files 2019-12-11 19:17:27 +01:00
mpu_userspace.rst kernel: delete separate logic for priv stacks 2020-03-17 20:11:27 +02:00
overview.rst doc: usermode: stack access policy change 2020-10-21 10:20:23 -07:00
syscall_flow.png
syscalls.rst doc: usermode: use zephyr_file to locate syscall_handler.h 2020-08-19 10:27:26 -07:00