path: root/docs/firmware-design.rst
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authorSoby Mathew <soby.mathew@arm.com>2018-06-01 16:53:38 +0100
committerSoby Mathew <soby.mathew@arm.com>2018-06-07 12:26:19 +0100
commitc099cd3942fb163a7894536c1ebaf4ffbf677a82 (patch)
treefbb3196da85758b6481031ef9ea8fef7c853865c /docs/firmware-design.rst
parentedcd266e6a9276ac0b2927301c8deec3798a6b1c (diff)
ARM platforms: Move BL31 below BL2 to enable BL2 overlay
The patch changes the layout of BL images in memory to enable more efficient use of available space. Previously BL31 was loaded with the expectation that BL2 memory would be reclaimed by BL32 loaded in SRAM. But with increasing memory requirements in the firmware, we can no longer fit BL32 in SRAM anymore which means the BL2 memory is not reclaimed by any runtime image. Positioning BL2 below BL1-RW and above BL31 means that the BL31 NOBITS can be overlaid on BL2 and BL1-RW. This patch also propogates the same memory layout to BL32 for AArch32 mode. The reset addresses for the following configurations are also changed : * When RESET_TO_SP_MIN=1 for BL32 in AArch32 mode * When BL2_AT_EL3=1 for BL2 The restriction on BL31 to be only in DRAM when SPM is enabled is now removed with this change. The update to the firmware design guide for the BL memory layout is done in the following patch. Change-Id: Icca438e257abe3e4f5a8215f945b9c3f9fbf29c9 Signed-off-by: Soby Mathew <soby.mathew@arm.com>
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