Is this actually supposed to work?

[derekchiang]

Sorry I pressed the comment button too quickly. Details follow:

I was trying to compile this repo according to the instructions given, but got lots of errors.

1. Some files, for instance arch/x86/cpu/gdt.rs, did not import kernel::memory::Allocator. As a result the alloc method couldn't be called.
2. The lib attribute does not work anymore. It was replaced by crate_id.
3. After fixing the previous two errors, which was easy enough, I got this:

/usr/bin/clang -O2 -ffreestanding -target i686-intel-linux -c boot/main.bc -o boot/main.o
clang: error: no such file or directory: 'boot/main.bc'
clang: error: no input files

At the first glance, there is indeed no such file. The file intended to be used seems to be rustboot.bc. So it indicates that there are some errors in the Makefile.

[derekchiang]

So I replaced main with rustboot in the Makefile and the compilation was able to proceed a little bit. Now I'm getting even weirder errors:

make all -C arch/x86/
make[1]: Entering directory `/media/Work_Study/CS/workspace/rust/rustboot/arch/x86'
/usr/bin/clang -O2 -ffreestanding -target i686-intel-linux -c boot/rustboot.bc -o boot/rustboot.o
/usr/bin/ld -melf_i386 -o boot/floppy.elf -T ./boot/linker.ld ./boot/loader.o ./boot/rustboot.o "-(" ./boot/libcore-2e829c2f-0.0.rlib "-)" -Map=././boot/linker.map
./boot/libcore-2e829c2f-0.0.rlib(core.o): In function `core::u64::mul_with_overflow':
/media/Work_Study/CS/workspace/rust/rustboot/arch/x86/../../rust-core/core/u64.rs:29: undefined reference to `__udivdi3'
./boot/libcore-2e829c2f-0.0.rlib(core.o): In function `core::i64::mul_with_overflow':
/media/Work_Study/CS/workspace/rust/rustboot/arch/x86/../../rust-core/core/i64.rs:35: undefined reference to `__mulodi4'
make[1]: *** [boot/floppy.elf] Error 1
make[1]: Leaving directory `/media/Work_Study/CS/workspace/rust/rustboot/arch/x86'
make: *** [all] Error 2

Any clue what's going on?

[pczarn]

This problem is caused by u64.rs and i64.rs, both can be removed in rust-core/core/lib.rs as a workaround. thestinger commented on f47d13b

You need clang with compiler-rt for udivdi3 and mulodi4. If you don't want to build position independent code you can pass -fno_pie.

I'm surprised your changes work, I got this:

$ make
make all -C arch/x86/
make[1]: Entering directory '/home/piotr/Desktop/rustboot/arch/x86'
make[1]: *** No rule to make target 'boot/rustboot.o', needed by 'boot/floppy.elf'.  Stop.
make[1]: Leaving directory '/home/piotr/Desktop/rustboot/arch/x86'
Makefile:4: recipe for target 'all' failed
make: *** [all] Error 2

[pczarn]

Just an idea, main.rs (perhaps you changed it to rustboot.rs) can be moved to kernel/lib.rs or arch/.../lib.rs.

[pczarn]

FAQ

Is this actually supposed to work?

Yes.

Is it any good?

Yes.

[derekchiang]

Indeed, I made some mistakes. Now the Makefile should work.

When I pass -fno_pie to ld, I get this error:

/usr/bin/ld -melf_i386 -fno_pie -o boot/floppy.elf -T ./boot/linker.ld ./boot/loader.o ./boot/main.o "-(" ./boot/libcore-2e829c2f-0.0.rlib "-)" -Map=././boot/linker.map
/usr/bin/ld: -f may not be used without -shared
make[1]: *** [boot/floppy.elf] Error 1

Do you know why?

[derekchiang]

Oh I misread the message. Thought it said with rather than without.

So I added -shared (without knowing what the consequences are) and it compiled. When I do make run though, all I see is a black screen flashing with the message:

Booting from Hard Disk...
Boot failed: could not read the boot disk

Booting from Floppy...

[pczarn]

compiler-rt

First, link compiler-rt runtime library that manipulates integers larger than 32 bits. I'm using x86_64 Arch Linux and clang package contains /usr/lib/clang/3.4/lib/linux/libclang_rt.full-x86_64.a. Unfortunately, it's incompatible with i386. Two options remain.

• Build clang with compiler-rt for i386[1][2].
• Download and unpack libclang-common-3.4-dev or extra/i686/clang

Then append path to libclang_rt.full-i386.a to LINK in Makefile.

no position independent code

I don't think it matters. Maybe add -fno-pie to CFLAGS. The code is first generated by clang, not ld!