[musl] User mode linux error when compiled with musl

[musl] User mode linux error when compiled with musl

[Johann Hanne]

Hi,

I'm compiling user mode linux (kernel 5.5) against musl (toolchain from 
musl.cc, tried gcc 6 and gcc 9) and getting the following error when 
booting:
--
Run /init as init process
userspace - ptrace set fp regs failed, errno = 14
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
--

build command: make ARCH=um LD_FLAGS_CMDLINE="-static" 
CROSS_COMPILE=x86_64-linux-musl-

run command: ./linux initrd=test.cpio.gz

test.cpio.gz contains a statically linked "Hello world" init, which 
works when UML is built against the host cc with glibc (Ubuntu 16.04, 
gcc 5, also with "-static").

Any ideas?

Regards,
   Johann

Re: [musl] User mode linux error when compiled with musl

[Rich Felker]

On Mon, Mar 30, 2020 at 07:21:48PM +0200, Johann Hanne wrote:
> Hi,
> 
> I'm compiling user mode linux (kernel 5.5) against musl (toolchain
> from musl.cc, tried gcc 6 and gcc 9) and getting the following error
> when booting:
> --
> Run /init as init process
> userspace - ptrace set fp regs failed, errno = 14
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> --
> 
> build command: make ARCH=um LD_FLAGS_CMDLINE="-static"
> CROSS_COMPILE=x86_64-linux-musl-
> 
> run command: ./linux initrd=test.cpio.gz
> 
> test.cpio.gz contains a statically linked "Hello world" init, which
> works when UML is built against the host cc with glibc (Ubuntu
> 16.04, gcc 5, also with "-static").
> 
> Any ideas?

Sorry, I don't have any and don't know enough about how UML works to
have a good guess. I'd start by trying to identify exactly where that
error message is coming from (probably somewhere in kernel code) and
look for what leads up to it.

Rich