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Binary compatibility

PostPosted: Mon Oct 08, 2007 2:31 pm
by Michael Tasche
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.
Since SP3 the binaries contain the symbol __cxa_finalize, which is not
part of the 6.2.1 libc.so.
e.g.:
ntoppc-nm hello | grep cxa
w __cxa_finalize

Binaries, build with 6.3.0 SP3, cannot be used under 6.2.1. You get
"unknown symbol: __cxa_finalize"

Binaries, build with 6.3.0 SP2, do not contain the above symbol and run
without problems under 6.2.1.

Was this intended?
I thought, if we loose binary compatibility, there would be a version
increment of e.g. libc.so.2 to libc.so.3.

Up to now I delivered only one binary, for customers using QNX
6.1.x...6.3.x.

Perhaps someone can clarify, how many binaries I have to deliver, to
support QNX 6.x.x.

Kind Regards
Michael

Re: Binary compatibility

PostPosted: Tue Oct 09, 2007 7:51 am
by Igor Kovalenko
They've probably just found out about it from your post.

"Michael Tasche" <michael.tasche@esd-electronics.com> wrote in message
news:8jrpt4-u9u.ln1@comm.esd...
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.
Since SP3 the binaries contain the symbol __cxa_finalize, which is not
part of the 6.2.1 libc.so.
e.g.:
ntoppc-nm hello | grep cxa
w __cxa_finalize

Binaries, build with 6.3.0 SP3, cannot be used under 6.2.1. You get
"unknown symbol: __cxa_finalize"

Binaries, build with 6.3.0 SP2, do not contain the above symbol and run
without problems under 6.2.1.

Was this intended?
I thought, if we loose binary compatibility, there would be a version
increment of e.g. libc.so.2 to libc.so.3.

Up to now I delivered only one binary, for customers using QNX
6.1.x...6.3.x.

Perhaps someone can clarify, how many binaries I have to deliver, to
support QNX 6.x.x.

Kind Regards
Michael

Re: Binary compatibility

PostPosted: Tue Oct 09, 2007 3:51 pm
by Mario Charest
"Michael Tasche" <michael.tasche@esd-electronics.com> wrote in message
news:8jrpt4-u9u.ln1@comm.esd...
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.
Since SP3 the binaries contain the symbol __cxa_finalize, which is not
part of the 6.2.1 libc.so.
e.g.:

I'm not sure but I beleive __cxa stuff is related to C++. Are you using
C++ code ( directly or indirectlry ), if so there is a new cpp library with
6.3.0 SP?

Re: Binary compatibility

PostPosted: Tue Oct 09, 2007 5:58 pm
by Michael Tasche
Mario Charest schrieb:
"Michael Tasche" <michael.tasche@esd-electronics.com> wrote in message
news:8jrpt4-u9u.ln1@comm.esd...
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.
Since SP3 the binaries contain the symbol __cxa_finalize, which is not
part of the 6.2.1 libc.so.
e.g.:

I'm not sure but I beleive __cxa stuff is related to C++. Are you using
C++ code ( directly or indirectlry ), if so there is a new cpp library with
6.3.0 SP?

No c++ code. The call executes the atexit handlers and seems to be
called from the c startup (crtbegin.o) since SP3.

Re: Binary compatibility

PostPosted: Tue Oct 09, 2007 8:55 pm
by David Gibbs
Michael Tasche <michael.tasche@esd-electronics.com> wrote:
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.

We do not generally promise (nor expect) that binaries built with a
later version of our dev tools will run on an earlier version of our OS.

-David
--
David Gibbs
QNX Training Services
dagibbs@qnx.com

Re: Binary compatibility

PostPosted: Tue Oct 09, 2007 9:08 pm
by Frank Liu
Michael Tasche <michael.tasche@esd-electronics.com> wrote:
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.

Binary compatibility usually means if it was built on an older
OS, it can still run on the newer OS. Not the other way around.

If you want the greatest compatibility, you should probably build
it on the oldest OS :)

Re: Binary compatibility

PostPosted: Thu Oct 11, 2007 9:46 am
by Michael Tasche
David Gibbs schrieb:
Michael Tasche <michael.tasche@esd-electronics.com> wrote:
Hi all,

I have just noticed, that my C applications have loosed binary
compatibility to 6.2.1, since I build them under 6.3.0 SP3.

We do not generally promise (nor expect) that binaries built with a
later version of our dev tools will run on an earlier version of our OS.
I understand that, but was there really a need to make this change in a

way, that we loose binary compatibility for every "Hello World"?

Well, I will try, to make my own cxa_xxx functions, which dlsym the the
originals from the 6.3 libc's.
Btw can someone explain the "weak" attribute of the cxa_xx symbols?


ntoppc-nm hello | grep cxa
w __cxa_finalize

Btw can someone explain the "w" attribute of the above symbol ?

-Michael


-David