eboot: .RODATA, upstream uzlib, move CRC, save 112 bytes #7844
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RODATA can be copied automatically by the bootrom, so no reason not to allow its use for strings and constants in eboot.c Revert to pfalcon's original uzlib since the single patch to remove RODATA is not required. Rationalize eboot.ld linker script, clean up BSS and init it in code. Saves 112 bytes of space in the bootloader sector by removing the extra code associated with literal loads.
earlephilhower force-pushed the eboot-rodata1 branch from c90082a to 4f19e27 Compare earlephilhower changed the title We added protection to only erase the bootload sector when flashing an image when the new sector != the old sector. This was intended to minimize the chance of bricking (i.e. if there was a powerfail during flashing of the boot sector the chip would be dead). Unfortunately, by placing the CRC inside the eboot sector *every* application will have a unique eboot sector (due to the crc/len), so this protection doesn't work. Move the CRC into the first 8 bytes of IROM itself. This frees up extra space in the boot sector and ensures that eboot won't be reflashed unless there really is an eboot change.
earlephilhower changed the title mcspr added a commit to mcspr/esp8266-Arduino that referenced this pull request Feb 3, 2021
mcspr reviewed Feb 3, 2021
The consequence of this move is that "checksum" (in write_bin) is not valid anymore, because the data is changed afterwards. |
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RODATA can be copied automatically by the bootrom, so no reason not to
allow its use for strings and constants in eboot.c
Revert to pfalcon's original uzlib since the single patch to remove
RODATA is not required.
Rationalize eboot.ld linker script, clean up BSS and init it in code.
Saves 112 bytes of space in the bootloader sector by removing the
extra code associated with literal loads.
Move CRC out of bootload sector
We added protection to only erase the bootload sector when flashing an
image when the new sector != the old sector. This was intended to
minimize the chance of bricking (i.e. if there was a powerfail during
flashing of the boot sector the chip would be dead).
Unfortunately, by placing the CRC inside the eboot sector every
application will have a unique eboot sector (due to the crc/len), so
this protection doesn't work.
Move the CRC into the first 8 bytes of IROM itself. This frees up extra
space in the boot sector and ensures that eboot won't be reflashed
unless there really is an eboot change.