This patch adds a new Kconfig option that allows read-only data sections
without relocations to be mapped directly (remain in flash) instead of
being copied to RAM during extension loading. This helps extensions that
have large constant data, such as certificates, lookup tables etc.. to
save saving significant RAM, especially with MPU is enabled.
This feature requires the extension to place rodata sections without
relocations in LLEXT_RODATA_NO_RELOC section.
Note that we chose to disable this optimization when MMU or USERSPACE is
enabled because the NO_RELOC section may not be aligned to the MPU/MMU
requirements on some architectures. If we leave it in place, llext will
attempt to create an MPU region for it using a misaligned address, and
if we allow it to be copied to RAM, it defeats the purpose of this feature.
Signed-off-by: Ibrahim Abdalkader <i.abdalkader@gmail.com>
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