X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/7afff55a7df3d64c09ebcf8bfaf6fbb12b288513..de637a122ac32df4af29078ee79995914a0e0b01:/doc/doxygen/inside_extending.doc

diff --git a/doc/doxygen/inside_extending.doc b/doc/doxygen/inside_extending.doc
index e4da841c1e..bb37b1d7e1 100644
--- a/doc/doxygen/inside_extending.doc
+++ b/doc/doxygen/inside_extending.doc
@@ -117,22 +117,38 @@ s_surf_model_description_t surf_plugin_description[] = {
 ~~~~
 
 \section simgrid_dev_guide_simcall How to add a new simcall?
-A simcall is used to go from user mode to kernel mode. The workflow of
-a simcall is the following:
+
+A simcall is used to go from user mode to kernel mode. There is some
+sort of popping dance involved, as we want to isolate the user
+contextes from their environment (so that they can run in parallel).
+
+The workflow of a simcall is the following:
 
 - `<ret> simcall_<name>(<args>)`
  - `simcall_BODY_<name>(<args>)`
-  - create the simcall
-  - `SIMIX_process_yield` if not maestro
+  - Initializes the simcall (store the arguments in position)
+  - If maestro, executes the simcall directly (and return)
+  - If not, call `SIMIX_process_yield` to give back the control to maestro
   - ========== KERNEL MODE ==========
-  - `SIMIX_simcall_enter`
-   - `SIMIX_pre_<name>(simcall, <args>)`
-   - `SIMIX_simcall_answer(simcall)`
-
-To simplify the simcall creation, we have made a python script that
-generate most of the code and give helpers for the remaining stuff.
-That script reads the simcall definitions from src/simix/simcalls.in 
-and generates the following files:
+  - `SIMIX_simcall_handle` large switch (on simcall) doing for each:
+   - `simcall_HANDLER_<name>(simcall, <args>)` (the manual code handling the simcall)
+   - If the simcall is not marked as "blocking" in its definition,
+     call `SIMIX_simcall_answer(simcall)` that adds back the issuer
+     process to the list of processes to run in the next scheduling round.
+     It is thus the responsability of the blocking simcalls to call
+     `SIMIX_simcall_answer(simcall)` themselves in their handler.
+
+Note that empty HANDLERs can be omitted. These functions usually do
+some parameter checking, or retrieve some information about the
+simcall issuer, but when there no need for such things, the handler
+can be omited. In that case, we directly call the function
+`simcall_<name>(<args>)`.
+
+To simplify the simcall creation, a python script generates most of
+the code and give helpers for the remaining stuff. That script reads
+the simcall definitions from src/simix/simcalls.in, checks that both
+`simcall_<name>()` and `simcall_HANDLER()` are defined somewhere, and
+generates the following files:
 
 - smx_popping_accessors.h:
   Helper functions to get and set simcall arguments and results
@@ -144,9 +160,6 @@ and generates the following files:
   Definitions of `simcall_names[]` (debug name of each simcall), and
   SIMIX_simcall_enter() that deals with the simcall from within the kernel
 
-Furthermode if the simcall_<name> or the SIMIX_pre_<name> function are missing,
-a warning will show up with a prototype of the corresponding fonction to fill.
-
 The simcall.in file list all the simcalls in sections. A line starting by "##"
 define a new section which will be replace by a "ifdef" in the generated code.
 There is a simcall by line which follow this format: