The following mechanisms are OSPM specific:
1. Redirect output destination to console: no file redirection will be
needed by an in-kernel debugger, there is even no file can be accessed
when the debugger is running in the kernel mode.
2. Output command prompts: programs other than acpiexec can have different
prompt characters and the prompt characters may be implemented as a
special character sequence to form a char device IO protocol.
3. Command ready/complete handshake: OSPM debugger may wait more conditions
to implement OSPM specific semantics (for example, FIFO full/empty
conditions for O_NONBLOCK or IO open/close conditions).
Leaving such OSPM specific stuffs in the ACPICA debugger core blocks
Linux debugger IO driver implementation.
Several new OSL APIs are provided by this patch:
1. acpi_os_initialize_command_signals: initialize command handshake mechanism
or any other OSPM specific stuffs.
2. acpi_os_terminate_command_signals: reversal of
acpi_os_initialize_command_signals.
3. acpi_os_wait_command_ready: putting debugger task into wait state when a
command is not ready. OSPMs can terminate command loop by returning
AE_CTRL_TERMINATE from this API. Normally, wait_event() or
wait_for_multiple_object() may be used to implement this API.
4. acpi_os_notify_command_complete: putting user task into running state when a
command has been completed. OSPMs can terminate command loop by
returning AE_CTRL_TERMINATE from this API. Normally, wake_up() or
set_event() may be used to implement this API.
This patch also converts current command signaling implementation into a
generic debugger layer (osgendbg.c) to be used by the existing OSPMs or
acpiexec, in return, Linux can have chance to implement its own command
handshake mechanism. This patch also implements acpiexec batch mode in a
multi-threading mode comaptible style as a demo (this can be confirmed by
configuring acpiexec into DEBUGGER_MULTI_THREADED mode where the batch mode
is still working). Lv Zheng.
Note that the OSPM specific command handshake mechanism is required by
Linux kernel because:
1. Linux kernel trends to use wait queue to synchronize two threads, using
mutexes to achieve that will cause false "dead lock" warnings.
2. The command handshake mechanism implemented by ACPICA is implemented in
this way because of a design issue in debugger IO streaming. Debugger IO
outputs are simply cached using a giant buffer, this should be tuned by
Linux in the future.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
f8d3148962