Lines Matching refs:ROM

1 Library at ROM
4 This document provides an overview of the "library at ROM" implementation in
10 The "library at ROM" feature allows platforms to build a library of functions to
11 be placed in ROM. This reduces SRAM usage by utilising the available space in
12 ROM. The "library at ROM" contains a jump table with the list of functions that
13 are placed in ROM. The capabilities of the "library at ROM" are:
17 2. Functions can be patched after they have been programmed into ROM.
19 3. Platform-specific libraries can be placed in ROM.
29 Library at ROM is described by an index file with the list of functions to be
30 placed in ROM. The index file is platform specific and its format is:
37     function -- Name of the function to be placed in library at ROM
60 When invoking a function of the "library at ROM", the calling sequence is as
63 BL image --> wrapper function --> jump table entry --> library at ROM
65 The index file is used to create a jump table which is placed in ROM. Then, the
66 wrappers refer to the jump table to call the "library at ROM" functions. The
71 The "library at ROM" contains a necessary init function that initialises the
72 global variables defined by the functions inside "library at ROM".
78 files for the "library at ROM" to work. It implements multiple functions:
84    variable (**not** the jump table itself) with the absolute address in ROM.
102 Patching of functions in library at ROM
108 "library at ROM" version of this function.
117 Using library at ROM will modify the memory layout of the BL images:
119 - The ROM library needs a page aligned RAM section to hold the RW data. This
124 - Depending on the functions moved to the ROM library, the size of the BL images
126   For example: moving MbedTLS function into the ROM library reduces BL1 and
132 Build library at ROM
140 to showcase the benefits of library at ROM - it's not mandatory.