From: "Vít Ondruch" <v.ondruch@...>
Date: 2013-12-12T23:40:13+01:00
Subject: [ruby-core:59079] Re: Ruby vs glibc-2.18.90 on ARM

Dne 12.12.2013 18:37, Yusuke Endoh napsal(a):
> Hello,
>
> 2013/12/11 V�t Ondruch <v.ondruch@gmail.com>:
>> When building Ruby for Fedora Rawhide, which ships glibc-2.18.90, the
>> test suite SIGABRTs when running on ARM. I originally reported the
>> issue against glibc [1] and now the discussion continues on glibc ML
>> [2]. Would anybody with more expertise how Ruby is using
>> setjmp/longjmp (and possibly makecontext/restorecontext) care to join
>> the discussion to help resolve the issue (prior glibc developers
>> declare the bug as Ruby's bug)?
>
> I glanced over the discussion.
> I know I should send this mail to that thread,
> but sorry for my laziness to investigate about the subscription.
>
>
> Ruby's GC is indeed exploiting setjmp to dump the registers to the heap.
> AFAIK this is a common hack for implementing a conservative GC.
> For example, Boehm GC also uses it.
>
> Unfortunately, the hack won't work when jmp_buf is mangled.
> It is mysterious if it works in other targets that use mangling...
> Boehm GC uses getcontext or _builtin_unwind_init instead of setjmp
> when they are available.  The former is not available in some platforms,
> and the latter is an extension of GCC, though.
>
> The following link shows a brief explanation about the topic.
> ("Additional requirements for a basic port" section)
>
> http://www.hpl.hp.com/personal/Hans_Boehm/gc/porting.html
>
> I think Ruby can use the same strategy of Boehm GC.
> I guess it is not so hard to implement it, but I could be wrong
> because I didn't read the Boehm GC's source code.
>

Thank you for your response. Neither I am registered on all ML, so I'll 
try forward you response via RH bugzilla and glibc maintainer.


V�t