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Re: Removal of unexec support from glibc malloc

On 01/18/2016 08:24 PM, Paul Eggert wrote:

> Can you explain the problem in more detail? What are the symptoms if you
> do the following with the next-generation glibc API?
> git clone --branch emacs-25 git://
> cd emacs
> ./
> ./configure
> make

This doesn't work with current glibc and the current Emacs
file.  It doesn't seem possible to get rid of the dlmalloc detection
without editing

> Is there some way that Emacs developers (who are typically not glibc
> experts) can easily test with the next-generation glibc API?

I don't have the new API yet.  It will likely consist of the C and POSIX
APIs exclusively (that is, no hooks, no malloc_set_state).  The easiest
way is likely to trick configure into believing that it's not on glibc
malloc.  If the resulting post-dump binary runs under valgrind or with
another malloc implementation such as jemalloc or tcmalloc preloaded, it
will likely work with future glibc versions.

I did the edit, and Emacs chose to use gmalloc.c, and the
resulting binary works, even under valgrind.  Looking at its symbols,
it's immune to malloc preloading due to the built-in malloc definition.
 This should continue to work, but you now have to maintain your own malloc.


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