Re: [boost] [context review] Several Questions

Subject: Re: [boost] [context review] Several Questions
From: Artyom (artyomtnk_at_[hidden])
Date: 2011-03-21 18:17:37

> > 

> > a) (BIG ONE) The shared object link using  fcontext crashes!
> > 
> >     Using  boost_1_46_0
> 
> boost-1.46 not tested - use 1.45, please

Sorry, I can't accept this, also because crash happens
inside boost_context function I don't think it is related
to 1.45 / 1.46 differences

> 
> >      Building boost_context:
> > 
> >     bjam toolset=gcc  context-impl=asm architecture=x86 
>instruction-set=native
> >  address-model=64 --with-context
> >          variant=release stage
> 
> which platform i386? Into the documention I provide  for all the platforms 
>(arm, i386, x86_64, mips, ppc) the bjam-options you have  to used.
> - for x86 64bit: bjam toolset=gcc architecture=x86  instruction-set=yorksfield 
>address-model=64 context-impl=asm
> 
> >      Then I compile example link.cpp
> > 
> >     Run  it
> > 
> >     It crashes!
> > 
> 
> not in my  test
> 

Unfortunately it is not so good answer :-) 

Fresh Build with bjam:

bjam toolset=gcc context-impl=asm architecture=x86 instruction-set=yorksfield 
address-model=64 --with-context stage

Build of program:

g++ -g -O3 -Wall link.cpp -I ../../boost_1_46_0 -L ../../boost_1_46_0/stage/lib/ 
-Wl,-rpath=../../boost_1_46_0/stage/lib/  -lboost_context -lrt

$ ./a.out 
Segmentation fault
$ gdb ./a.out 
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/artik/Packages/boost/reviews/bc/a.out...done.
(gdb) r
Starting program: /home/artik/Packages/boost/reviews/bc/a.out 
[Thread debugging using libthread_db enabled]

Program received signal SIGSEGV, Segmentation fault.
0x00000000006033f0 in get_fcontext ()
(gdb) bt
#0  0x00000000006033f0 in get_fcontext ()
#1  0x00000000004018cd in context () at 
../../boost_1_46_0/boost/context/context.hpp:68
#2  main () at link.cpp:24

Starting program: /home/artik/Packages/boost/reviews/bc/a.out 
[Thread debugging using libthread_db enabled]

Program received signal SIGSEGV, Segmentation fault.
0x00000000006033f0 in get_fcontext ()

I'd suggest to dig deeper because it can have very critical effect
on how reviewers will see this library.

> this is  not my fault - boost.build in its current version

No more explanations required... I know all drawbacks of BBv2 and accept as
fully reasonable answer! (When do we move to CMake?..)

> Do mean why you can specify to use the context swapping provided  by the
> Operating System or the assembler code (==fcontext)?

I mean something like

boost::context<> // some default
boost::ucontext<>
boost::fcontext<>

So you can have two implementations in same code.

Thanks,
  Artyom