On Wed, Jun 22, 2016 at 12:18:56AM +0200, Adam Lackorzynski wrote:

...

I tried to build fiasco on alpine linux. This will fail with the following line:

auto/jdb_ktrace.cc:1:0: error: code model kernel does not support PIC mode

Just this file or more/all files?

Not sure. The build stopped after the first error and I was not able to reconfigure for ignoring that file.

...

Their gcc enables PIC per default for security reasons. Since fiasco seems to need PIC disabled I have to tell the build system either to add -fno-PIC explictly, or to -D__KERNEL__ in any way. (I already tried DEFINES += -D__KERNEL__ or CFLAGS := -fno-PIC in Makeconf without success.)

What is the correct way to add such an option to the fiasco build system? Would it hurt to add -D__KERNEL__ per default on future releases? (After all it *is* a kernel.)

I'd add this to src/Makeconf: SHARED_FLAGS += -fno-pic

Does this fix it?

Not completely. Now compiling seem to work fine, but linking will run into problems:

==> Linking fiasco.image boot_img.o: In function `bootstrap_bootstrap': (.bootstrap.text+0x98): relocation truncated to fit: R_X86_64_32 against symbol `_start' defined in .text section in crt0.o kip_init-ia32.o: In function `Kip_init::init()': kip_init-ia32.cc:(.initcall.text+0x33): relocation truncated to fit: R_X86_64_32 against symbol `my_kernel_info_page' defined in .kernel_info_page section in kip_init-ia32.o kip_init-ia32.cc:(.initcall.text+0xd8): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image kip_init-ia32.cc:(.initcall.text+0xe8): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x27d): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x30b): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x33d): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x37e): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image libabi.a(kip.o): In function `Kip::add_mem_region(Mem_desc const&)': kip.cc:(.text+0x61): relocation truncated to fit: R_X86_64_32 against `.rodata.str1.8' thread-ia32.o: In function `Thread::handle_int3(Trap_state*)': thread-ia32.cc:(.text+0x55): relocation truncated to fit: R_X86_64_32 against `.rodata.str1.1' thread-ia32.cc:(.text+0x14e): additional relocation overflows omitted from the output .../kernel/fiasco/src/boot/amd64/Makerules.BOOT.amd64:29: recipe for target 'fiasco.image' failed

The above output is from building with 'make SHARED_FLAGS=-D__KERNEL__'. There is a bit more noise with -fno-pic or -fno-PIC, but it is the same kind of problem.

Any idea what exactly is going on here?

On Fri, Jun 24, 2016 at 12:05:43AM +0200, Adam Lackorzynski wrote:

I gave this a try with Alpine 3.4 and just the -fno-pic addition made it compile for me. However, the error message while compiling was different. Thus: Which version do you use?

I'm currently using a fresh install of the current Alpine 3.4. Everything is amd64.

$ uname -a Linux alpine 4.4.11-0-grsec #1-Alpine SMP Fri May 20 08:35:18 GMT 2016 x86_64 Linux $ gcc --version gcc (Alpine 5.3.0) 5.3.0

I use am minimally configured fiasco from the current public snapshot.

tar xf l4re-snapshot-2016060908.tar.bz2 make -C l4re-snapshot-2016060908/src/kernel/fiasco/ B=$PWD/fiasco echo "CONFIG_AMD64=y" >fiasco/globalconfig.out make -C fiasco olddefconfig make -C fiasco V=0 SHARED_FLAGS=-fno-pic

This results in:

==> Linking fiasco.image boot_img.o: In function `bootstrap_bootstrap': (.bootstrap.text+0x98): relocation truncated to fit: R_X86_64_32 against symbol `_start' defined in .text section in crt0.o boot_img.o: In function `bootstrap_bootstrap': (.bootstrap.text+0x39b): undefined reference to `__stack_chk_fail' boot_img.o: In function `bootstrap__Z14base_cpu_setupv': (.bootstrap.text+0x5b0): undefined reference to `__stack_chk_fail' boot_img.o: In function `bootstrap_printf': (.bootstrap.text+0xb09): undefined reference to `__stack_chk_fail' boot_img.o: In function `bootstrap_vprintf': (.bootstrap.text+0xb7e): undefined reference to `__stack_chk_fail' boot_img.o: In function `bootstrap___v_printf': (.bootstrap.text+0x141a): undefined reference to `__stack_chk_fail' kip_init-ia32.o: In function `Kip_init::init()': kip_init-ia32.cc:(.initcall.text+0x25): relocation truncated to fit: R_X86_64_32 against symbol `my_kernel_info_page' defined in .kernel_info_page section in kip_init-ia32.o kip_init-ia32.cc:(.initcall.text+0xe8): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image kip_init-ia32.cc:(.initcall.text+0xf8): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x2a5): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x32b): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x36c): relocation truncated to fit: R_X86_64_32 against symbol `_kernel_image_start' defined in .kip section in fiasco.image kip_init-ia32.cc:(.initcall.text+0x3a3): relocation truncated to fit: R_X86_64_32 against symbol `_end' defined in .bss section in fiasco.image kip_init-ia32.o:kip_init-ia32.cc:(.initcall.text+0x3ce): more undefined references to `__stack_chk_fail' follow libabi.a(kip.o): In function `Kip::add_mem_region(Mem_desc const&)': kip.cc:(.text+0x61): relocation truncated to fit: R_X86_64_32 against `.rodata.str1.8' thread-ia32.o: In function `Thread::handle_int3(Trap_state*)': thread-ia32.cc:(.text+0x55): relocation truncated to fit: R_X86_64_32 against `.rodata.str1.1' thread-ia32.cc:(.text+0x14e): additional relocation overflows omitted from the output .../l4re-snapshot-2016060908/src/kernel/fiasco/src/boot/amd64/Makerules.BOOT.amd64:29: recipe for target 'fiasco.image' failed

If I replace '-fno-pic' with '-D__KERNEL__' it will no longer complain about the undefiend reference, but still complain about the trucated relocation.

It is no big problem if it does not compile on this kind of system. It only felt like there might be an easy fix.

On Mon, Jun 27, 2016 at 12:49:10AM +0200, Adam Lackorzynski wrote:

Please use this instead of specifying SHARED_FLAGS on the command line. Otherwise all of the flags that are set in the Makefiles are missing.

Oh, you are of course completely right. :) Now it seems to work fine. Thanks for the help.

Michael