From 112a3f2de281a2afb23ced2082d555720de7c9b0 Mon Sep 17 00:00:00 2001 From: Shao Miller Date: Sat, 23 Jan 2010 22:12:27 -0500 Subject: [pxe] Introduce PXE exit hook for NBP chaining It might be the case that we wish to chain to an NBP without being "in the way". We now implement a hook in our exit path for gPXE *.*pxe build targets. The hook is a pointer to a SEG16:OFF16 which we try to jump to during exit. By default, this pointer results in the usual exit path. We also implement the "pxenv_file_exit_hook" PXE API routine to allow the user to specify an alternate SEG16:OFF16 to jump to during exit. Unfortunately, this additional PXE extension has a cost in code size. Fortunately, a look at the size difference for a gPXE .rom build target shows zero size difference after compression. The routine is documented in doc/pxe_extensions as follows: FILE EXIT HOOK Op-Code: PXENV_FILE_EXIT_HOOK (00e7h) Input: Far pointer to a t_PXENV_FILE_EXIT_HOOK parameter structure that has been initialized by the caller. Output: PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be returned in AX. The Status field in the parameter structure must be set to one of the values represented by the PXENV_STATUS_xxx constants. Description:Modify the exit path to jump to the specified code. Only valid for pxeprefix-based builds. typedef struct s_PXENV_FILE_EXIT_HOOK { PXENV_STATUS_t Status; SEGOFF16_t Hook; } t_PXENV_FILE_EXIT_HOOK; Set before calling API service: Hook: The SEG16:OFF16 of the code to jump to. Returned from API service: Status: See PXENV_STATUS_xxx constants. Requested-by: H. Peter Anvin Signed-off-by: Shao Miller Signed-off-by: Marty Connor --- src/doc/pxe_extensions | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'src/doc') diff --git a/src/doc/pxe_extensions b/src/doc/pxe_extensions index 92269cfc..8ff14a95 100644 --- a/src/doc/pxe_extensions +++ b/src/doc/pxe_extensions @@ -277,3 +277,36 @@ Provider: Set to 0x45585067 ("gPXE"). Another implementation of this APIMask: Bitmask of supported API functions (one bit for each function in the range 00e0h to 00ffh). Flags: Set to zero, reserved for future use. + + + + +FILE EXIT HOOK + +Op-Code: PXENV_FILE_EXIT_HOOK (00e7h) + +Input: Far pointer to a t_PXENV_FILE_EXIT_HOOK parameter + structure that has been initialized by the caller. + +Output: PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be + returned in AX. The Status field in the parameter + structure must be set to one of the values represented + by the PXENV_STATUS_xxx constants. + +Description: Modify the exit path to jump to the specified code. + Only valid for pxeprefix-based builds. + +typedef struct s_PXENV_FILE_EXIT_HOOK { + PXENV_STATUS_t Status; + SEGOFF16_t Hook; +} t_PXENV_FILE_EXIT_HOOK; + + +Set before calling API service: + +Hook: The SEG16:OFF16 of the code to jump to. + + +Returned from API service: + +Status: See PXENV_STATUS_xxx constants. -- cgit v1.2.3-55-g7522