Re: SYS_sbrk removal proposal

[Sevan Janiyan <venture37%geeklan.co.uk@localhost>]

Hello,

On 12/19/17 11:51, Anders Magnusson wrote:
> Sounds good :-)
> 
> Just a note here:
> 
> about 15-20 years ago I did a test by removing the brk(2) syscall and
> replacing its use
> in malloc() by mmap(), and also add a libc wrapper for brk() that
> mmap'ed MAXDSIZ/2 if ever called (as a fallback).
> 
> This approach worked very well for everything tested _except_ emacs.
> There were something in emacs dump logic that seemed to expect that
> brk() were continuing just above bss, or something.
> I didn't go deeper into this back then.
> 
> Anyway, it might be an idea to revisit this.  IMHO it would be really
> nice if brk(2) could be declared obsolete :-)

Just as a heads up, I believe the FreeBSD folks went through this with
their ARMv8 support and looking up the notes on their wiki, indeed,
emacs was the fallout.
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213862

Sevan