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@@ -0,0 +1,285 @@ + GNU libc SNAPSHOT SYSTEM + (general info) + Updated 1997-9-26 + +WHAT ARE GNU libc SNAPSHOTS +--------------------------- + +Snapshots are an "image" of the main glibc 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 libc that is no more than one day older than +the official source tree used by the libc maintainers. + +The primary purpose of providing snapshots is to widen the group of motivated +developers that would like to help test, debug, and enhance glibc, 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 + glibc hosts and targets. If a new bug is introduced in glibc 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 glibc 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 glibc'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 glibc 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 glibc + 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 glibc 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 glibc, you can use the snapshot versions in your + daily work, but users who have not been consulted about whether they + feel like testing glibc 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 glibc 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. + + +WHO SHOULD TRY THE SNAPSHOTS +---------------------------- + +Remember, these are snapshots not tested versions. So if you use +these versions you should be able to + + o make sure your system stays usable + + o locate and hopefully fix problems + + o to port glibc to a new target yourself + +You should not use the snapshots if + + o your system is needed in a production environment which needs + stability + + o you expect us to fix your problems since you somehow depend on them. + You must be willing to fix the problems yourself, we don't want to + see "I have problems, fix this" messages. + + +HOW TO GET THE SNAPSHOTS +------------------------ + +At the moment we provide a full snapshot weekly (every sunday), so +that users getting a snapshot for the first time, or updating after +a long period of not updating, can get the latest version in a single +operation. Along with the full snapshot, we will provide incremental +diffs on a nearly daily basis (whenever code changes). Each daily +diff will be relative to the source tree after applying all previous +daily diffs. The daily diffs are for people who have relatively low +bandwidth ftp or uucp connections. + +The files will be available via anonymous ftp from alpha.gnu.ai.mit.edu, in +directory /gnu/libc and on linux.kernel.org in /pub/software/libs/glibc. The +directories should look something like: + + libc-970921.tar.gz + libc-970917-970922.diff.gz + libc-970922-970925.diff.gz + . + . + . + +Please note that the snapshots on alpha.gnu.ai.mit.edu and on +linux.kernel.org are not always in sync. Patches to some files might +appear a day a diff earlier or later on alpha than on kernel. +Use always alpha or always kernel but don't mix them. + +There are sometimes additionally test releases of the add-ons available in +these directories. If a new version of an add-on is available it is normally +required for the corresponding snapshot so always pay attention for these. + +Note that we provide GNU gzip compressed files only. You can ftp gzip +from prep.ai.mit.edu in directory pub/gnu. + +In some cases the dates for diffs and snapshots do not match like in the +example above. The full release is for 970921 but the patch is for +970917-970922. This only means that nothing changed between 970917 and 970922 +and that you have to use this patch on top of the 970921 snapshot since the +patch is made on 970922. + +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 glibc user base naively attempts to use the snapshots, has trouble with +them, complains publically, and the reputation of glibc declines because of a +perception of instability or lack of quality control. + + +GLIBC TEST SUITE +---------------- + +A test suite is distributed as an integral part of the snapshots. A simple +"make check" in your build directory is sufficient to run the tests. glibc +should pass all tests and if any fails, please report it. A failure might not +originate from a bug in glibc but also from bugs in the tools, e.g. with gcc +2.7.2.x the math tests fail some of the tests because of compiler bugs. + +Note that the test suite is still in its infancy. The tests themselves only +cover a small portion of libc features, and where tests do exist for a feature +they are not exhaustive. New tests are welcome. + + +GETTING HELP, GLIBC DISCUSSIONS, etc +------------------------------------ + +People who want to help with glibc and who test out snapshots regularly should +get on the libc-alpha@gnu.ai.mit.edu mailing list by sending an email to +libc-alpha-request@gnu.ai.mit.edu. This list is meant (as the name suggests) +for the discussion of test releases and also reports for them. People who are +on this list are welcome to post questions of general interest. + +People who are not only willing to test the snapshots but instead really want +to help developing glibc should contact libc-hacker-request@gnu.ai.mit.edu to +be put on the developers mailing list. This list is really only meant for +developers. No questions about installation problems or other simple topics +are wanted nor will they be answered. + +Do *not* send any questions about the snapshots or patches specific to the +snapshots to bug-glibc@prep.ai.mit.edu. Nobody there will have any idea what +you are talking about and it will just cause confusion. + + +BUG REPORTS +----------- + +Send bug reports directly to Ulrich Drepper <drepper@gnu.ai.mit.edu>. Please +do *not* use the glibcbug script for reporting bugs in the snapshots. +glibcbug should only be used for problems with the official released versions. +We don't like bug reports in the bug database because otherwise the impression +of instability or lack of quality control of glibc as a whole might manifest +in people's mind. + +Note that since no testing is done on the snapshots, and snapshots may even be +made when glibc is in an inconsistent state, it may not be unusual for an +occasional snapshot to have a very obvious bug, such as failure to compile on +*any* machine. It is likely that such bugs will be fixed by the next +snapshot, so it really isn't necessary to report them unless they persist for +a couple of days. + +Missing files should always be reported, since they usually mean there is a +problem with the snapshot-generating process and we won't know about them +unless someone tells us. + +Bugs which are non-obvious, such as failure to compile on only a specific +machine, a new machine dependent or obscure bug (particularly one not detected +by the testsuite), etc should be reported when you discover them, or have a +suggested patch to fix them. + + +FORMAT FOR PATCHES +------------------ + +If you have a fix for a bug, or an enhancement to submit, send your patch to +Ulrich Drepper <drepper@gnu.ai.mit.edu>. Here are some simple guidelines for +submitting patches: + + o Use "unified diffs" for patches. A typical command for generating + context diffs is "diff -ru glibc-old glibc-patched". + + 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 + glibc ChangeLog for examples of what a ChangeLog entry should look + like. The emacs command ^X4A will create a ChangeLog entry header + for you. + + +BUILDING SNAPSHOTS +------------------ + +The `best' way to build glibc is to use an extra directory, e.g.: +tar xzf libc-970921.tar.gz +mkdir build-glibc +cd build-glibc +../libc-970921/configure ... + +In this way you can easily clean up (since `make clean' doesn't work at +the moment) and rebuild glibc. + + +NECESSARY TOOLS +--------------- + +For the recommended versions of gcc, binutils, make, texinfo, gettext, +autoconf and other tools which might be especially needed when using patches, +please read the file INSTALL. + + +HOW CAN YOU HELP +---------------- + +It helps already a lot if you just install glibc on your system and try to +solve any problems. You might want to look at the file `PROJECTS' and help +with one of those projects, fix some bugs (see `BUGS' or the bug database), +port to an unsupported platform, ... + + +FURTHER DOCUMENTATION +--------------------- + +A lot of questions are answered in the FAQ. The files `INSTALL', `README' and +`NOTES' contain the most important documentation. Furthermore glibc has its +own 700+ pages info documentation, ... + + + +And finally a word of caution: The libc is one of the most fundamental parts +of your system - and these snapshots are untested and come without any +guarantee or warranty. You might be lucky and everything works or you might +crash your system. If you install a glibc snapshot as primary library, you +should have a backup somewhere. + +On many systems it is also a problem to replace the libc while the system is +running. In the worst case on broken OSes some systems crash. On better +systems you can move the old libc aside but removing it will cause problems +since there are still processes using this libc image and so you might have to +check the filesystem to get rid of the libc data. One good alternative (which +is also safer) is to use a chroot'ed environment. + +Thanks for your help and support. + +Thanks to Fred Fish from Cygnus for the original version of this text +(for GDB). + + +Ulrich Drepper |