Re: dynamic linker command line invocation

[N Jain <jain61@gmail.com>]

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Hi Marcus,

Thanks. I am able to get this part working.
I am facing one more issue during dynamic linking and need some help to
understand how to resolve it.

In below code part of __dls3 function I found that TPIDRURO register is
being used to read the threadId.
I would like to understand how kernel should set this value ?

As per my understanding kernel should allocate memory and set this register
for current task.
But when i do this in my kernel the values doesn't match up as MUSL is
using some "builtin_tls" ?

/* Temporarily set the tls size to the full size of
* builtin_tls so that __copy_tls will use the same layout
* as it did for before. Then check, just to be safe. */
libc.tls_size = sizeof builtin_tls;
if (__copy_tls((void*)builtin_tls) != self) a_crash();

Thanks,
NJ


On Fri, Jan 8, 2016 at 6:09 AM, Markus Wichmann <nullplan@gmx.net> wrote:

> On Thu, Jan 07, 2016 at 06:29:48PM -0500, N Jain wrote:
> > Hi Rich,
> >
> > Thanks I am able to get my dynamic linker loaded into memory but facing
> > issue during application load at __dls3 function.
> > I am getting following print from MUSL -
> >
> > "musl libc
> > Version 1.1.10
> > Dynamic Program Loader
> > Usage: hello.elf [options] [--] pathname--2--"
> >
> > Not sure why my application is not getting loaded in below code __dls3
> > function ?
> >
>
> That's what I was trying to tell you in my first answer: You need to set
> argv[0] to something (doesn't matter so long as it's not "ldd"), and
> argv[1] to the program file you want to run. (And argc to 2, obviously).
>
> The only alternative to that is to load the program file in the kernel
> additionally to musl, and then set the following aux vectors:
>
> AT_BASE - base address of dynamic linker
> AT_PHDR - address of main executable's program headers
> AT_PHNUM, AT_PHENT - number and size of main executable's program
> headers, respectively.
> AT_ENTRY - main executable's entry point
>
> Ciao,
> Markus
>

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