It is not really needed; g_hart_stacks is only used during SBI init as
a temporary stack area. We can use the scratch area buffers for this, as
the scratch areas define almost 4K of extra space, which is used for
exception stacks anyway.
Polarfire Icicle board has only (128K - 256) bytes for the bootloader
in the non-volatile eNVM. This space is barely enough for running NuttX.
If OpenSBI is selected, it will be placed in DDR. This all means the
nuttx.bin file grows into gigabyte size, filling the unused space (ddr -
envm) with zeroes.
The memory layout is as follows:
MEMORY
{
ddr (rx) : ORIGIN = 0x80000000, LENGTH = 4M
envm (rx) : ORIGIN = 0x20220100, LENGTH = 128K - 256
l2lim (rwx) : ORIGIN = 0x08000000, LENGTH = 1024k
l2zerodevice (rwx) : ORIGIN = 0x0A000000, LENGTH = 512k
}
OpenSBI library is used as a separate binary, which is stored into
eMMC or SD-card. It is then loaded into its precise location in DDR.
Thus, we separate OpenSBI from NuttX and end up with two images
by utilizing the objcopy options:
--only-section=sectionpattern (-j in short)
--remove-section=sectionpattern (-R in short)
This is only valid when CONFIG_MPFS_OPENSBI is set.
Signed-off-by: Eero Nurkkala <eero.nurkkala@offcode.fi>
Ville Juven