linker: sort app shared mem partition by alignment
If CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT is enabled,
the app shared memory partition may cause waste of memory
due to the need for padding.
For example, tests/subsys/jwt and board mps2_an385:
z_test_mem_partition: addr 0x20000000, size 52
z_libc_partition : addr 0x20000040, size 4
k_mbedtls_partition : addr 0x20008000, size 32736
ending at 0x2000ffff, taking up 65536 bytes
With power-of-two size and alignment requirement,
k_mbedtls_partition takes up 32KB memory and needs to be
aligned on 32KB boundary. If the above partitions are
ordered as shown, there needs to be a lot of padding
after z_libc_partition before k_mbedtls_partition can
start. In order to minimize padding, these partitions
need to be sort by size in descending order.
After the changes here, the partitions are:
k_mbedtls_partition : addr 0x20000000, size 32736
z_test_mem_partition: addr 0x20008000, size 52
z_libc_partition : addr 0x20008040, size 4
ending at 0x2000805f, taking up 32864 bytes
With the above example, sorting results in a saving
of 32672 bytes of saving.
Fixes #14121
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
6 files changed
