GDB SNAPSHOT SYSTEM
			    (general info)
			   Updated 4/21/93

WHAT ARE GDB SNAPSHOTS

Snapshots are an "image" of the main GDB development tree, captured at a
particular random instant in time.  When you use the snapshots, you should
be able to maintain a local copy of GDB that is no more than one day older
than the official source tree used by the GDB maintainers.

The primary purpose of providing snapshots is to widen the group of
motivated developers that would like to help test, debug, and enhance GDB,
by providing you with access to the "latest and greatest" source.
This has several advantages, and several disadvantages.

    First the advantages:

    o	Once we have a large base of motivated testers using the snapshots,
	this should provide good coverage across all currently supported
	GDB hosts and targets.  If a new bug is introduced in GDB due to
	fixing another bug or ongoing development, it should become 
	obvious much more quickly and get fixed before the next general
	net release.  This should help to reduce the chances of GDB being
	released to the general public with a major bug that went unnoticed
	during the release cycle testing because they are machine dependent.
	We hope to greatly improve GDB's stability and reliability by
	involving more people and more execution environments in the
	prerelease testing.

    o	With access to the latest source, any diffs that you send to fix
	bugs or add new features should be much easier for the GDB team
	to merge into the official source base (after suitable review
	of course).  This encourages us to merge your changes quicker,
	while they are still "fresh".

    o	Once your diffs are merged, you can obtain a new copy of GDB
	containing your changes almost immediately.  Thus you do not
	have to maintain local copies of your changes for any longer
	than it takes to get them merged into the official source base.
	This encourages you to send in changes quicker.

    And the disadvantages:

    o	The snapshot you get will be largely untested and of unknown quality.
	It may fail to configure or compile.  It may have serious bugs.
	You should always keep a copy of the last known working version
	before updating to the current snapshot, or at least be able to
	regenerate a working version if the latest snapshot is unusable
	in your environment for some reason.

	If a production version of GDB has a bug and a snapshot has the fix,
	and you care about stability, you should put only the fix for that
	particular problem into your production version.  Of course, if you
	are eager to test GDB, you can use the snapshot versions in your
	daily work, but users who have not been consulted about whether they
	feel like testing GDB should generally have something which is at
	least as bug free as the last released version.

    o	Providing timely response to your questions, bug reports, and
	submitted patches will require the GDB development team to allocate
	time from an already thin time budget.  Please try to help us make
	this time as productive as possible.  See the section below about
	how to submit changes.


HOW TO GET THE SNAPSHOTS

The current plan is to provide a full snapshot once weekly, and incremental
diffs on a daily basis.  Each daily diff will be relative to the source
tree for the previous day after applying all incremental diffs to date.

The files will be available via anonymous ftp from ftp.cygnus.com, in
directory pub/gdb, and should look something like:

	gdb-930401.tar.z
	gdb-930401-930402.diff.z
	gdb-930402-930403.diff.z
	gdb-930403-930404.diff.z
	.
	.
	.

At some point, the files should automatically appear during the evening
as a result of an automatically run process each evening.  For the moment
however, the process will be manually run by one of the gdb maintainers
and the appropriate files moved to the ftp area at some convenient point
during the day.

Note that the current plan is to provide gzip compressed files only, on the
theory that serious GDB testers and developers should have no problem 
acquiring and installing a copy of GNU gzip.  We may revisit this issue if
it turns out to be a problem.  You can ftp GNU gzip from prep.ai.mit.edu
in directory pub/gnu.

Also, as the gcc developers did with their gcc snapshot system, even though
we will make the snapshots available on a publically accessible ftp area,
we ask that recipients not widely publicise their availability.  The motivation
for this request is not to hoard them, but to avoid the situation where
the general GDB user base naively attempts to use the snapshots, has trouble
with them, complains publically, and the reputation of GDB declines because
of a perception of instability or lack of quality control.


GDB TEST SUITE

A test suite is distributed as an integral part of the snapshots.  However,
to use it you will need to get a copy of the dejagnu testing framework.
Snapshots of dejagnu are available alongside the GDB snapshots, using
the same naming conventions as the GDB snapshots.  Once you have installed
the dejagnu framework, a simple "make check" in the GDB directory should
be sufficient to run the tests.

Note that the test suite is still in its infancy.  The test framework
itself might not install on your system if you have an environment that
is not similar to one that the GDB developers already use.  The tests
themselves only cover a small portion of GDB features, and what tests
do exist for a feature are not exhaustive.  New tests are welcomed.


HOW TO SUBMIT CHANGES

Patches should be sent to gdb-patches@cygnus.com.  Questions about the
snapshots themselves, problems accessing the snapshots, etc can also be sent
to the same email address.  One of the GDB team members will take on the
responsibility of responding to your questions or submitted patches.

Do *not* send any questions about the snapshots or patches specific to
the snapshots to bug-gdb@prep.ai.mit.edu (gateway'd to the usenet group
gnu.gdb.bug).  Nobody there will have any idea what you are talking about
and it will just cause confusion.

Here are some simple guidelines for submitting patches:

    o	Use "context diffs" for patches.  A typical command for generating
	context diffs is "diff -rc gdb-old gdb-new".

    o	Use the "minimalist approach" for patches.  That is, each patch
	should address only one particular bug, new feature, etc.  Do not
	save up many unrelated changes and submit them all in one big
	patch, since in general, the larger the patch the more difficult
	it is for us to decide if the patch is either correct or
	desirable.  And if we find something about the patch that needs
	to be corrected before it can be installed, we would have to reject
	the entire patch, which might contain changes which otherwise would
	be accepted if submitted separately.

    o	Submit a sample ChangeLog entry with your patch.  See the existing
	GDB ChangeLog for examples of what a ChangeLog entry should look
	like.  The emacs command ^X4A will create a ChangeLog entry header
	for you.

Thanks for your help and support.

-Fred Fish
 Cygnus Support