Re: Dumper problems and a possible solutions

[Rich Felker <dalias@libc.org>]

On Thu, Jun 26, 2014 at 07:02:40AM +0400, Dmitry Antipov wrote:
> BTW, if you're doing your own libc, why do not implement Solaris-style dldump()?

Because dumping isn't really possible to do in a correct and
meaningful way without serious restrictions on what the code can do.
See Eli Zaretskii's email (Message-id: <83simspexv.fsf@gnu.org>)
stating that "Emacs cannot use such libraries." For a single
application like Emacs that's a decision that can be made. But to say
"[X feature of] libc can't support such code" when the code is
perfectly valid C is not really appropriate.

There's all sorts of state that cannot be preserved across dumping but
that's completely reasonable to have, such as pid, lock owners (tids
will not be the same after a dump), open files, etc. At one point I
actually tried to do a Solaris-style forkall() -- I mention this
because it has a lot of the same issues -- and partly had it working,
but the lock ownership issue turned out to be impractical to solve and
I abandoned it.


Rich