It turns out that, when written into a ROM image, the BSS was expanded into actual zeroed bytes copied that were into flash (the BIOS loader on the PSP doesn't do any interpretation of the payload; it just copies bytes, so it kind of has to do this). This took up unnecessary space in flash.
But we already zero the BSS and map it explicitly, so just relocate it before the text segment and mark it NOLOAD in the linker script (and make some trivial corresponding adjustments in the mapping code). Et voila, we save a few megabytes of flash.
dancrossnyc
commented
6 months ago
It turns out that, when written into a ROM image, the BSS was expanded into actual zeroed bytes copied that were into flash (the BIOS loader on the PSP doesn't do any interpretation of the payload; it just copies bytes, so it kind of has to do this). This took up unnecessary space in flash.
But we already zero the BSS and map it explicitly, so just relocate it before the text segment and mark it NOLOAD in the linker script (and make some trivial corresponding adjustments in the mapping code). Et voila, we save a few megabytes of flash.