Split GM9 across two sections in memory. #837
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This is needed to implement support for Lua. Lua is way to big to fit in
a single contigious section of memory without overwriting our copy of
boot9 and boot11, so some clever linker manipulation was used to place
things in the free space after it.
This uses the following memory map:
```
AHBWRAM: 0x08000000 - 0x08080000
.vectors
.text
.ARM.exidx
AHBWRAM2: 0x080a0000 - 0x08100000
.text (files in arm9/source/lua)
.rodata
.data
.bss
```
Makefile
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| $(OUTDIR)/AHBWRAM.bin: $(ELF) | ||
| @$(OBJCOPY) -O binary arm9/arm9.elf --only-section=AHBWRAM $@ | ||
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| $(OUTDIR)/AHBWRAM2.bin: $(ELF) | ||
| @$(OBJCOPY) -O binary arm9/arm9.elf --only-section=AHBWRAM2 $@ | ||
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| BINS := $(OUTDIR)/AHBWRAM.bin $(OUTDIR)/AHBWRAM2.bin | ||
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| firm: $(ELF) $(BINS) | ||
| @mkdir -p $(call dirname,"$(FIRM)") $(call dirname,"$(FIRMD)") | ||
| @echo "[FLAVOR] $(FLAVOR)" | ||
| @echo "[VERSION] $(VERSION)" | ||
| @echo "[BUILD] $(DBUILTL)" | ||
| @echo "[FIRM] $(FIRM)" | ||
| @$(PY3) -m firmtool build $(FIRM) $(FTFLAGS) -g -D $(ELF) -C NDMA XDMA | ||
| @$(PY3) -m firmtool build $(FIRM) $(FTFLAGS) -g -D $(BINS) arm11/arm11.elf \ | ||
| -A 0x08000000 0x080a0000 -C NDMA NDMA XDMA -n 0x08000040 | ||
| @echo "[FIRM] $(FIRMD)" | ||
| @$(PY3) -m firmtool build $(FIRMD) $(FTDFLAGS) -g -D $(ELF) -C NDMA XDMA | ||
| @$(PY3) -m firmtool build $(FIRMD) $(FTDFLAGS) -g -D $(BINS) arm11/arm11.elf \ | ||
| -A 0x08000000 0x080a0000 -C NDMA NDMA XDMA -n 0x08000040 |
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Just out of curiosity, is there way you'd like for this to actually be done?
Hardcoding the the entry-point here also seems quite fragile but I doubt that will suddenly break us unless for some reason we move move _start or increase the size of .vectors.
| $(OUTDIR)/AHBWRAM_LO.elf: $(ELF) | ||
| @$(OBJCOPY) arm9/arm9.elf -j AHBWRAM_LO $@ | ||
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| $(OUTDIR)/AHBWRAM_HI.elf: $(ELF) | ||
| @$(OBJCOPY) arm9/arm9.elf -j AHBWRAM_HI $@ |
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objcopy is now throwing a warning and it does not provide any option to silence it.
Since this doesn't break the build, do you have any suggestions on how I can silence its output, or if we can even do so?
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Trying some stuff with this PR and I think a few features aren't working properly. Specifically I tried building a CIA for a built-in title (Activity Log USA 0004001000021200), and it froze. Building the latest commit of the main repo (ad8b5e0) and it works fine. Is there a chance something else is using arm9 memory? Or is something just weird with my setup? I don't know what else could have broken. |
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Maybe related to lto? Because building the latest mainline commit without lto results in a crash: |
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I'd consider opening a separate issue for that. This reeks of UB. |
turns out the freeze here was actually the exception handler being broken due to a typo in the linker script. this has been fixed |
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Wolfvak has offered a much better solution than what is present here. Closing this. |
This is needed to implement support for Lua. Lua is way to big to fit in a single contiguous section of memory without overwriting our copy of boot9 and boot11, so some clever linker manipulation was used to place things in the free space after it. LTO also had to be disabled as we won't be able to split
.textlater with it.This uses the following memory map:
This has been tested on actual hardware and seems to boot up and work fine.