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Diffstat (limited to 'docs/porting-guide.rst')
| -rw-r--r-- | docs/porting-guide.rst | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst index 21db86bde..c35c52675 100644 --- a/docs/porting-guide.rst +++ b/docs/porting-guide.rst @@ -1076,20 +1076,16 @@ warm boot. For each CPU, BL1 is responsible for the following tasks: allocation to BL2 meminfo.free_size = Size of secure RAM available for allocation to BL2 - BL1 places this ``meminfo`` structure at the beginning of the free memory - available for its use. Since BL1 cannot allocate memory dynamically at the - moment, its free memory will be available for BL2's use as-is. However, this - means that BL2 must read the ``meminfo`` structure before it starts using its - free memory (this is discussed in Section 3.2). + By default, BL1 places this ``meminfo`` structure at the beginning of the + free memory available for its use. Since BL1 cannot allocate memory + dynamically at the moment, its free memory will be available for BL2's use + as-is. However, this means that BL2 must read the ``meminfo`` structure + before it starts using its free memory (this is discussed in Section 3.2). - In future releases of the ARM Trusted Firmware it will be possible for - the platform to decide where it wants to place the ``meminfo`` structure for - BL2. - - BL1 implements the ``bl1_init_bl2_mem_layout()`` function to populate the - BL2 ``meminfo`` structure. The platform may override this implementation, for - example if the platform wants to restrict the amount of memory visible to - BL2. Details of how to do this are given below. + It is possible for the platform to decide where it wants to place the + ``meminfo`` structure for BL2 or restrict the amount of memory visible to + BL2 by overriding the weak default implementation of + ``bl1_plat_handle_post_image_load`` API. The following functions need to be implemented by the platform port to enable BL1 to perform the above tasks. @@ -1264,6 +1260,12 @@ This function can be used by the platforms to update/use image information corresponding to ``image_id``. This function is invoked in BL1, both in cold boot and FWU code path, after loading and authenticating the image. +The default weak implementation of this function calculates the amount of +Trusted SRAM that can be used by BL2 and allocates a ``meminfo_t`` +structure at the beginning of this free memory and populates it. The address +of ``meminfo_t`` structure is updated in ``arg1`` of the entrypoint +information to BL2. + Function : bl1\_plat\_fwu\_done() [optional] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |