how does Fiasco achieve C++ support

Adam Lackorzynski adam at os.inf.tu-dresden.de
Sat Jun 27 23:30:26 CEST 2015


On Fri Jun 26, 2015 at 19:01:21 -0400, Yuxin Ren wrote:
> Hi,
> 
>  I just want to make sure that you do not misunderstand my questions.
> All my questions are related the user level, that is l4re, not the kernel.

Ok, I see, when you mention Fiasco I always think of the kernel. So for
userland:

Regarding new/delete: No changes
Regarding modifying libstdc++, libsupc++ and libgcc: No changes, except
libgcc on ARM where Linux specific atomic ops are exchanged with L4
ones.
Regarding locks: We build against pthreads.

> One more question, does Fiasco provide its owner gthred wrappers to the gcc?

No.


Adam


> On Fri, Jun 26, 2015 at 6:34 PM, Adam Lackorzynski
> <adam at os.inf.tu-dresden.de> wrote:
> > On Fri Jun 26, 2015 at 22:44:07 +0800, Yuxin Ren wrote:
> >> You said Fiasco implements its own new/delete operator, could you show
> >> me where the code for those is?
> >
> > There are several placement new's, for example in thread.cpp and
> > task.cpp. Just look for "operator new" in those files.
> >
> >> In addition, does Fiasco modify the code of libstdc++, libsupc++ and libgcc?
> >
> > Fiasco, the kernel, does not use libstdc++ nor libsupc++, and it also
> > does not modify libgcc as far as it is using it.
> >
> >> I think inside those libraries, they may use locks. And we need to use
> >> the Fiasco's lock implementation, not Linux's.
> >
> > Generally, libstdc++ does not depend on Linux, it can for example also
> > use pthreads internally.
> >
> >> Another confusion comes from the local static object. In order to
> >> guarantee its constructor only run once, the compiler will insert
> >> lock around the constructor. but does the gcc know which lock
> >> implementation to use?
> >
> > This is disabled by using -fno-threadsafe-statics.
> >
> >
> >
> >
> > Adam
> > --
> > Adam                 adam at os.inf.tu-dresden.de
> >   Lackorzynski         http://os.inf.tu-dresden.de/~adam/
> >
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-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/



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