Re: cvs commit: src/include string.h src/lib/libc/string Makefile.inc memchr.3 memrchr.c src/sys/sys param.h

From: Robert Watson <rwatson_at_FreeBSD.org>
Date: Fri, 30 May 2008 16:11:28 +0100 (BST)
On Fri, 30 May 2008, Alexander Leidinger wrote:

>>>> So, this is neither a vote for nor against a backout, but this is a 
>>>> general call to resist the conservative tendancy that says "don't MFC 
>>>> minor things" because, in macro, it has a significant drag effect on the 
>>>> MFC process that keeps RELENG branches maintainable.
>>> 
>>> Ok, but consider the prior email with kan about MFC's after an 8.0 
>>> release. Since you must be able to run 7.x binaries on 8.0, then you can't 
>>> MFC any symbol changes from 8.0+ back to 7.x.  The symbols are basically 
>>> frozen in 7.x after 8.0 is released.
>> 
>> Sounds like a bug.  :-)
>
> We have the possibility of this behavior even in older releases. Imagine a 
> 8.0 release and a 8.1 release before a 7.4 release. And let 8.1 have a 
> symbol which is not available in 8.0 (MF9). Now let's MFC this symbol to 
> 7-stable before 7.4. Boom, you can not run a 7.4 binary which uses this 
> symbol on 8.0.
>
> More or less it comes down to be careful about things to MFC (don't MFC 
> symbols to the second last branch).

I think everyone is fine with "you must be careful".  What I think some of us 
would be less fine with is "you can't do it at all".

Robert N M Watson
Computer Laboratory
University of Cambridge
Received on Fri May 30 2008 - 15:11:30 UTC