Re: [uml-devel] current_thread_info() returns invalid pointer in early UML boot code

[Richard W. <ri...@no...>]

Am 12.06.2016 um 22:59 schrieb Vegard Nossum:
> On 12 June 2016 at 22:11, Richard Weinberger
> <ric...@gm...> wrote:
>>> I wonder why setup_env_path() ends up calling the kernel's snprintf(),
>>> I thought that it would be using the glibc snprintf() at this point?
>>
>> That early you cannot use current() nor any other core kernel stuff
>> since the kernel has not started so far.
>> So, the current thread info struct points to garbage.
> 
> Yes, I know. I think setup_env_path() should call the libc snprintf
> rather than the kernel one, can you explain how to do that properly?

Currently UML sets up nasty maps for known namespaces clashes.
i.e.
KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
        $(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap      \
        -Din6addr_loopback=kernel_in6addr_loopback \
        -Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr

A much better approach would be having a real linker scope.
Some time ago I posted some thoughts on that:
https://lkml.org/lkml/2015/11/19/758

Due to -ENOTIME this never materialized, though. ;-(

Thanks,
//richard