Re: GDB 8.3.1 gdbserver linker error: needs -lrt

On 2020-01-31 12:23 p.m., Paul Smith wrote:
> On Fri, 2020-01-31 at 19:17 +0200, Eli Zaretskii wrote:
>>> In this case, we need a new library to link gdbserver directly, not
>>> because of some other package that gdbserver depends on, so we
>>> don't have a package that might contain a pkg-config we could use.
>>
>> Sorry, I thought liblzma needed -lrt.  Apologies if I was confused.
> 
> Oh I see the confusion.
> 
> No, you're absolutely right, liblzma DOES need -lrt.  And indeed, we DO
> use pkg-config to get info about liblzma.
> 
> And that's why linking of gdb itself succeeds: it links lzma with its
> pkg-config options and that causes -lrt to be linked, as a side-effect.
> 
> However, I'm whinging about gdbserver (and libinproctrace.so), and
> liblzma is not not linked into those, and so neither is -lrt.

I have tried to reproduce the build failure using a Docker container of
Centos 6.10.  I used the gcc 8 toolchain from softwarecollections.org,
and didn't see the undefined reference to clock_gettime.  This is despite
the system running glibc 2.12, and the clock_gettime man page saying that
-lrt is needed to use clock_gettime for glibc < 2.17.

Anyway, I suppose adding this to gdbserver's configure.ac would help, could
you try?

  AC_SEARCH_LIBS ([clock_gettime], [rt])

Simon