begin Sean Neakums quotation:
> begin Sean Neakums quotation:
>> begin Austin Gonyou quotation:
>>> No, It does not guarantee. Also, if you're not on the same Inode the
>>> file time is different, etc, it's possible to have different md5sums. A
>>> basic size and file comparison is probably best for what you want to do.
>> The md5sum of a file is based on its contents only. The inode has
>> nothing to do with it.
>>> Something you can do to test what I'm talking about is copy each of your
>>> dumps to another name, binfilexyz.1 or something, then compare it's
>>> md5sum against the original. Those should be the only time they match.
>> I'm not sure exaclty what you mean by this. The name of the file is
>> irrelevant in the computation of the md5sum.
> In Emacs' case, there's a niggle with this: if there's already an
> emacs-21.1.1 file there, it'll dump as emacs-21.1.2, and the dumped
> file will have that version embedded in it. The script I was using to
> generate the ms5sum was aware of this, and deleted the dumped files
> before each dump, so that the dump always happened to the name
> emacs-21.1.1. However, there is a variable, emacs-build-time, which
> contains the exact time the dump occurred. So md5sums are no use anyway.
> Funnily, the last file dump I did worked correctly at the time, but is
> now segfaulting, some hours later.
> I was doing the dumps while running three instances of this program,
> which I hacked up in a hurry, to generate lots of dirty pages and
> actual I/O: http://zork.net/~sneakums/io-test.c
> I wonder if the pages that are modified by the dump are not being
> written to disk correctly? This last dump was in a D state for a few
> minutes while the three io-test instances were running, but it did
> complete and seemingly start up correctly a few minutes after I killed
I think I can finally reproduce the bogus dumps. I just did it here,
three times. What I did was: run the io-test program above on two
different files for approx three minutes, then start the emacs dump.
When the dump completed, I started a third io-test and left the three
of them run for about five or so more minutes. What I'm trying to do
with all this I/O is to force the dumped binary's pages to be written
So after the five minutes or so, I killed the io-test threads and
attempted to start the dumped binary, which failed with a `cannot
execute' message from the shell. I looked in the file, and it pure
garbage: not even an "ELF" string at the start of the file.
I am now going to do a build of the upstream source and see if I can
make the dump break on that too. I'm hopeful that it will, as the
unexec code is the same in upstream as in the Debian emacs21 package.
///////////////// | | The spark of a pin
<sneakums@xxxxxxxx> | (require 'gnu) | dropping, falling feather-like.
\\\\\\\\\\\\\\\\\ | | There is too much noise.