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→ELF format: updated descriptions to not be as outdated
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== ELF format ==
== ELF format ==
−IOS modules, at least, use bare [[ELF]] files. The files seem to be compiled with GCC 3.4.3, and they are EABI compliant. The file is in big endian format. All ELF files are stripped and don't include function names or symbols.
+Individual IOS modules use bare [[ELF]] files. The files seem to be compiled with GCC 3.4.3, and they are EABI compliant. The file is in big endian format. All ELF files are stripped and don't include function names or symbols.
=== ELF Note Structure ===
=== ELF Note Structure ===
−IOS modules are loaded by the kernel (syscall load_module) according to an ELF note. There are exactly as many IOSELFNoteData as threads created by IOS.
+IOS modules in the main binary are loaded by the main kernel thread according to an ELF note. There are exactly as many IOSELFNoteData as process main threads in IOS.
<source lang="c">
<source lang="c">
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−=== BOOT2 elf loader ===
+=== Official ELF loaders ===
+The [[boot2]] and [[IOS]] elf stub loaders seem to be position-independent: they can be loaded at any address and will still work, as long as it doesn't overlap with the destination of the ELF load.
−The BOOT2 elf stub loader sets up a stack, calculates its own address, and switches to THUMB mode. Then it does the following:
+The official ELF loaders set up a stack and calculate their own address, switches to THUMB mode, and then they do the following:
<source lang="c">
<source lang="c">
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This sets the [[Hollywood/Registers#HW_SRNPROT|HW_SRNPROT]] register to enable the [[Starlet/Main Memory|SRAM]] mirror at 0xFFFE0000.
This sets the [[Hollywood/Registers#HW_SRNPROT|HW_SRNPROT]] register to enable the [[Starlet/Main Memory|SRAM]] mirror at 0xFFFE0000.
−After this, it loads the ELF file, and then '''zeroes out the memory area where the ELF file resides'''. Then it goes back to ARM mode and vectors to 0xFFFF0000 (the entrypoint of the ARM / vector table). The entire BOOT2 code seems to be position-independent: it can be loaded at any address and will still work, as long as it doesn't overlap with the destination of the ELF load. The entire BOOT2 file cleartext is loaded and then the loader is called, so the loader can calculate the offset of the header simply by subtracting 0x10 from the PC at its entrypoint.
+After this, it loads the ELF file, and then '''zeroes out the memory area where most of the ELF loader resides'''. Then it goes back to ARM mode and vectors to 0xFFFF0000 (the entrypoint of the ARM / vector table). The entire BOOT2 file cleartext is loaded and then the loader is called, so the loader can calculate the offset of the header simply by subtracting 0x10 from the PC at its entrypoint.
=== Embedded Broadway Code ===
=== Embedded Broadway Code ===