PATCH: Add --size-check=[error|warning]
(H.J. Lu, did you drop me from the Cc: line?)
Quoted 18 lines · Jan Beulich
Quoted 7 lines
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Please make it so that it'll be a warning by default, and an error upon programmer request. Otherwise, for the very purpose of
I disagree. It should be error by default since the input is bogus, Otherwise, those assembly bugs, benign or not, may not get fixed.
Quoted 6 lines
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bisection, it won't help much as you would have to override compiler/assembler flags during that process.
They can use a wrapper to pass --size-check=warning to assembler. I think it is a small price to pay for those mistakes.
"Small" being relative here - it could be dozens if not hundreds of people having to learn that this is necessary, many of them possibly rather unfamiliar with gas and its command line options.
Quoted 5 lines
Also, using a wrapper gets further complicated by the fact that you may have to pass an extra -B to the compiler (not everyone has full control over the file system of all the machines used to do development), making sure this doesn't have any other unwanted side effects.
Correct. In reality if the kernel does not build or boot then most people just wont continue with the bisection. So this change actively degrades debuggability, for no good reason.
The thing is, it is absolutely, breath-takingy incompetent for the new binutils version to break the Linux kernel build for 4 years of Linux kernel history retroactively (130,000 commits), just to 'warn' about a size bug in a few debug symbols that has no functional effects whatsoever and which few people care about.
The correct solution is to turn it into a warning as me and others have suggested.
No argument was offered *why* the build must be aborted. A warning serves the purpose of informing the developer just as much - and does not inconvenience the tester.
Thanks,
Ingo
Quoted 1 line · Ingo Molnar
The thing is, it is absolutely, breath-takingy incompetent for
kernel developers to write such poor asm! And not notice the error for 4 years! Oh, and the binutils developers to write such a poor assembler in the first place. ;-)
Seriously, you are complaining because something is fixed??
Quoted 1 line
The correct solution is to turn it into a warning as me and others have suggested.
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
Signature · 2 lines
Alan Modra Australia Development Lab, IBM
Hi Alan,
Quoted 7 lines · Alan Modra
Quoted 1 line · Ingo Molnar
The thing is, it is absolutely, breath-takingy incompetent for
kernel developers to write such poor asm! And not notice the error for 4 years! Oh, and the binutils developers to write such a poor assembler in the first place. ;-)
Quoted 7 lines
Seriously, you are complaining because something is fixed??
Quoted 1 line
The correct solution is to turn it into a warning as me and others have suggested.
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Pekka
Quoted 8 lines
Quoted 1 line
Quoted 1 line · Alan Modra
Quoted 1 line · Ingo Molnar
The thing is, it is absolutely, breath-takingy incompetent for
kernel developers to write such poor asm! And not notice the error for 4 years! Oh, and the binutils developers to write such a poor assembler in the first place. ;-)
Quoted 8 lines
Seriously, you are complaining because something is fixed??
Quoted 1 line
The correct solution is to turn it into a warning as me and others have
suggested.
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
Just to repeat what I said in a previous reply - an error should be issued if it is impossible for the assembler to produce valid output. Anything less severe should be a warning.
In the case given, as also stated before, simply not issuing anything to the object file if .size has an invalid operand is quite feasible for the assembler to do, and won't produce invalid output. The warning tells the programmer that not everything (s)he intended to be in the object file actually made it there.
Jan
Quoted 2 lines · Pekka Enberg
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Andreas.
Signature · 3 lines
Andreas Schwab, [email protected] GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E "And now for something completely different."
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
Pekka
Quoted 6 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 6 lines
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
I'm just telling you the facts.
Andreas.
Signature · 3 lines
Andreas Schwab, [email protected] GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E "And now for something completely different."
Quoted 6 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 6 lines
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
The claim is not even true.
While really old Linux versions wont build with fresh versions of Make, something like v2.6.30, which is a 2 years old kernel, will build just fine, using latest Make.
So lets stop coming up with all the wrong reasons to not fix this problem ...
Thanks,
Ingo
Quoted 8 lines · Andreas Schwab
Quoted 6 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 8 lines
Quoted 6 lines · Andreas Schwab
Quoted 2 lines
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
I'm just telling you the facts.
And you are wrong - latest Make does not break reasonably old kernel builds such as v2.6.30.
Latest binutils insta-breaks the build over 130,000 commits, including the latest released kernel.
Please change that .size build error to a build warning, to avoid this unnecessary collateral damage.
Thanks,
Ingo
Quoted 5 lines · Alan Modra
Quoted 1 line · Ingo Molnar
The thing is, it is absolutely, breath-takingy incompetent for
kernel developers to write such poor asm! And not notice the error for 4 years! [...]
It is not 'poor asm'.
The 'bug' is just a slight assymetry in ENTRY()/END() debug-symbols sequences, with lots of assembly code between the ENTRY() and the END(). Here's an example:
ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
...
END(do_hypervisor_callback)
Human reviewers almost never catch such small mismatches, and binutils never even warned about it either - for over a decade.
Now kernel bisections are insta-broken on latest binutils, and there's nothing to do about it on the kernel side as during bisection all later fixes are unfolded. The fix itself i already applied - but my argument was not about that:
Quoted 4 lines
[...] Oh, and the binutils developers to write such a poor assembler in the first place. ;-)
Seriously, you are complaining because something is fixed??
No, i reported this bug because the kernel build gets broken going back 130,000 commits, breaking bisection and causing other damage - while issuing a warning message would achieve the same effect of warning the developer about the mismatch.
Quoted 5 lines
Quoted 1 line
The correct solution is to turn it into a warning as me and others have suggested.
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
It's not about a switch at all - it's to not break builds by default. I.e. the default behavior should be to issue a warning and ignore the directive.
This is a very simple concept of compatibility: the build environment should always be very permissive - stuff that build fine before should be allowed to build.
Also, i hope you are not suggesting to break projects just because they are not important to you personally? The fix is exceedingly simple to do for the binutils project - and impossible to do for the kernel project (because during bisection - which is a very powerful debugging tool - older versions of the source get checked out).
Thanks,
Ingo
(resend, fixed the To line)
Quoted 5 lines · Alan Modra
Quoted 1 line · Ingo Molnar
The thing is, it is absolutely, breath-takingy incompetent for
kernel developers to write such poor asm! And not notice the error for 4 years! [...]
It is not 'poor asm'.
The 'bug' is just a slight assymetry in ENTRY()/END() debug-symbols sequences, with lots of assembly code between the ENTRY() and the END(). Here's an example:
ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
...
END(do_hypervisor_callback)
Human reviewers almost never catch such small mismatches, and binutils never even warned about it either - for over a decade.
Now kernel bisections are insta-broken on latest binutils, and there's nothing to do about it on the kernel side as during bisection all later fixes are unfolded. The fix itself i already applied - but my argument was not about that:
Quoted 4 lines
[...] Oh, and the binutils developers to write such a poor assembler in the first place. ;-)
Seriously, you are complaining because something is fixed??
No, i reported this bug because the kernel build gets broken going back 130,000 commits, breaking bisection and causing other damage - while issuing a warning message would achieve the same effect of warning the developer about the mismatch.
Quoted 5 lines
Quoted 1 line
The correct solution is to turn it into a warning as me and others have suggested.
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
It's not about a switch at all - it's to not break builds by default. I.e. the default behavior should be to issue a warning and ignore the directive.
This is a very simple concept of compatibility: the build environment should always be very permissive - stuff that build fine before should be allowed to build.
Also, i hope you are not suggesting to break projects just because they are not important to you personally? The fix is exceedingly simple to do for the binutils project - and impossible to do for the kernel project (because during bisection - which is a very powerful debugging tool - older versions of the source get checked out).
Thanks,
Ingo
Quoted 14 lines · Ingo Molnar
Quoted 12 lines · Andreas Schwab
Quoted 10 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Quoted 6 lines
Quoted 4 lines
Quoted 2 lines
Are you saying it's OK to screw over binutils users because GNU Make did that too?
I'm just telling you the facts.
And you are wrong
This is just ridiculous. You are defining away facts just because they don't fit your view.
Quoted 2 lines
latest Make does not break reasonably old kernel builds such as v2.6.30.
$ git tag --contains 3c955b4 | head -1 v2.6.36
Andreas.
Signature · 3 lines
Andreas Schwab, [email protected] GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E "And now for something completely different."
git bisect plus fixes (was: PATCH: Add --size-check=[error|warning])
In reply to Ingo Molnar[ adding the git list; this is
http://thread.gmane.org/gmane.comp.gnu.binutils/52601/focus=1112779 ]
Hello,
* Ingo Molnar wrote on Mon, Mar 14, 2011 at 01:23:42PM CET:
Quoted 5 lines
Also, i hope you are not suggesting to break projects just because they are not important to you personally? The fix is exceedingly simple to do for the binutils project - and impossible to do for the kernel project (because during bisection - which is a very powerful debugging tool - older versions of the source get checked out).
FWIW, I don't have an opinion on this particular binutils issue, but it would be very helpful if 'git bisect' made it easy to denote "when going back, you might also need some of these changes". (I'd just use a patch -p1 with a here-file in the bisect script, but that might not be enough for all practical use cases.)
This issue has come up several times with high-profile issues.
Thanks,
Ralf
Quoted 19 lines · Andreas Schwab
Quoted 17 lines · Ingo Molnar
Quoted 15 lines · Andreas Schwab
Quoted 12 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
Quoted 7 lines
Quoted 4 lines
Quoted 1 line
I'm just telling you the facts.
And you are wrong - latest Make does not break reasonably old kernel builds such as v2.6.30.
This is just ridiculous.
You are defining away facts just because they don't fit your view.
No, i actually tried out the latest released Make version (3.82) and it still builds v2.6.30 fine:
LD arch/x86/boot/setup.elf
OBJCOPY arch/x86/boot/setup.bin
BUILD arch/x86/boot/bzImage
Root device is (8, 1)
Setup is 12364 bytes (padded to 12800 bytes). System is 3730 kB
CRC 77bb7f2d
Kernel: arch/x86/boot/bzImage is ready (#105830)
The kernel build count is at 105830 because i build and test a lot of kernels on this box.
And the resulting kernel boots fine on a testbox:
mercury:~> uname -a
Linux mercury 2.6.30 #105830 SMP Mon Mar 14 12:29:06 CET 2011 x86_64 x86_64 x86_64 GNU/Linux
I have built and booted over half a million Linux kernels in the past 3-4 years so i generally have quite a bit of experience when it comes to build environment bugs and workflow problems. Breaking the build retroactively and unnecessarily like here is one of the worst things that can be done to testing quality and efficiency.
Thanks,
Ingo
Quoted 23 lines · Ingo Molnar
Quoted 21 lines · Andreas Schwab
Quoted 19 lines · Ingo Molnar
Quoted 16 lines · Andreas Schwab
Quoted 6 lines · Pekka Enberg
Hi Andreas,
Quoted 2 lines · Pekka Enberg
Quoted 2 lines
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Quoted 6 lines
Quoted 2 lines · Andreas Schwab
The same that testers have to do in order to build old Linux kernel versions with current versions of make.
Are you saying it's OK to screw over binutils users because GNU Make did that too?
I'm just telling you the facts.
Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
And you are wrong - latest Make does not break reasonably old kernel builds such as v2.6.30.
This is just ridiculous.
You are defining away facts just because they don't fit your view.No, i actually tried out the latest released Make version (3.82) and it still builds v2.6.30 fine:
That's a very convincing argument.
Andreas.
Signature · 3 lines
Andreas Schwab, [email protected] GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E "And now for something completely different."
Quoted 6 lines
Quoted 3 lines
I disagree. The whole world is not the linux kernel. I think HJ is bending over backwards to even offer a switch that turns the error into a warning.
So what do you suggest that testers who want to, say, build old Linux kernel versions with new binutils do?
Use an older binutils. It's already the case you can't build old kernels with current gcc and binutils, there have been repeated such events over time and nobody has had too much trouble.
Alan
PATCH 1/1 Document 'git bisect fix'.
In reply to Ralf Wildenhuesgit bisect is sometimes less effective than it could be in projects with long-lived but simple bugs (e.g., little-tested configurations). Rather than skipping vast revision ranges, it might be easier to fix them up from known bugfix branches.
'git bisect fix' teaches bisect about when some known bug was introduced and when it was fixed, so that bisect can merge in the fix when needed into new test candidates.
---
* Ralf Wildenhues wrote on Mon, Mar 14, 2011 at 02:16:23PM CET:
Quoted 2 lines
it would be very helpful if 'git bisect' made it easy to denote "when going back, you might also need some of these changes".
Merging in a set of bugfix branches (branches with minimal fixes, based right off of commits introducing some bug) before testing a particular contender would be a good start. Of course we don't want some bugfix branch to be merged in if the known bug isn't yet in the current contender, so as to not merge unrelated changes.
Cherry-pick things is another option, but the above seems a bit more gittish to me, and works well with bugfix branches. Also, data like "bugzilla X was introduced by C1 and fixed by C2" is helpful (and already available in some projects) anyway in a semi-automatic fashion. You might even want to version it, or keep it in project meta-data.
If some bug was fixed by a merge only, the more general notation "f_1 ^b_1 ^b_1' ..." could apply.
Here's a balloon doc patch to show what I mean. Comments? Is this too unlike how bisect works today? Too dangerous?
Thanks, and please keep me in Cc:,
Ralf
Documentation/git-bisect.txt | 20 ++++++++++++++++++++ git-bisect.sh | 4 +++- 2 files changed, 23 insertions(+), 1 deletions(-)
Documentation/git-bisect.txt +20 -0
@@ -25,6 +25,7 @@ on the subcommand: git bisect replay <logfile> git bisect log git bisect run <cmd>... + git bisect fix [(<range>|<rev>)...] This command uses 'git rev-list --bisect' to help drive the binary search process to find which change introduced a bug, given an
@@ -198,6 +199,25 @@ $ git bisect skip v2.5 v2.5..v2.6 This tells the bisect process that the commits between `v2.5` included and `v2.6` included should be skipped. +Fixing up known bugs +~~~~~~~~~~~~~~~~~~~~ + +If many revisions are broken due to some unrelated but known issue that +is easily fixed, you might want to prefer fixing it up temporarily. +If `<commit1>` introduces a bug fixed by `<commit2>`, instruct bisect +to merge the latter before testing a commit that contains the former: + +------------ +$ git bisect fix <commit1>..<commit2> +------------ + +A single `<commit>` acts as if `<commit>^..<commit>` was specified. +Fix statements can be repeated for every known bug, and are valid until +the bisection state is cleaned up with reset. + +Any bisect action that causes a new commit to be chosen will try to merge +the needed fixes and fail if they do not merge cleanly. + Cutting down bisection by giving more parameters to bisect start ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
git-bisect.sh +3 -1
@@ -1,6 +1,6 @@ #!/bin/sh -USAGE='[help|start|bad|good|skip|next|reset|visualize|replay|log|run]' +USAGE='[help|start|bad|good|skip|fix|next|reset|visualize|replay|log|run]' LONG_USAGE='git bisect help print this long help message. git bisect start [<bad> [<good>...]] [--] [<pathspec>...]
@@ -11,6 +11,8 @@ git bisect good [<rev>...] mark <rev>... known-good revisions. git bisect skip [(<rev>|<range>)...] mark <rev>... untestable revisions. +git bisect fix [(<c1>..<c2>|<rev>)...] + mark descendants of <c1>/<rev^> as needing fixes <c2>/<rev>. git bisect next find next bisection to test and check it out. git bisect reset [<commit>]
Signature · 1 line
1.7.4.1.231.ge4ce
Re: [PATCH] Document 'git bisect fix'.
Hi Ralf,
Maybe you should have made it more obvious that this patch is a RFC for a proposed feature (say, in subject line).
Quoted 3 lines
'git bisect fix' teaches bisect about when some known bug was introduced and when it was fixed, so that bisect can merge in the fix when needed into new test candidates.
This sounds like a great idea. I do have myself to do conditional cherry-picks from bisect scripts, to deal with this problem.
Quoted 2 lines
If some bug was fixed by a merge only, the more general notation "
f_1^b_1 ^b_1' ..." could apply.
Some more precise example may make this case more clear.
+Fixing up known bugs
+~~~~~~~~~~~~~~~~~~~~
+
+If many revisions are broken due to some unrelated but known issue that +is easily fixed, you might want to prefer fixing it up temporarily.
It seems natural for "bisect run" to use this mechanism. What about the non-automated process ? We may want to get the fixes applied, or to only list available fixes to the user so he can "git merge" them manually, or maybe an interactive selection mode ? Probably something to be chosen via some config variable and flags, in a separate patch of the would-be series. But what happens initially will be a good thing to document.
+If <commit1> introduces a bug fixed by <commit2>, instruct bisect +to merge the latter before testing a commit that contains the former:
+
+------------
+$ git bisect fix <commit1>..<commit2>
+------------
Usually, a bug also gets fixed by an official commit which does not fulfill the constraint of being branched at the faulty one. In this case you don't want to merge the fix if such a fix is already included, and thus you will need a way to specify "alternate fixes" to control this.
+A single <commit> acts as if <commit>^..<commit> was specified. +Fix statements can be repeated for every known bug, and are valid until +the bisection state is cleaned up with reset.
That is on the safe side, but we may at some point want some sort of "repository of fixes", where this info gets stored for easy reuse on subsequent bisections.
+Any bisect action that causes a new commit to be chosen will try to merge +the needed fixes and fail if they do not merge cleanly.
maybe "... similar to what happens when a bisect-run script terminates with exit code greated than 127." ?
Signature · 1 line
Yann Dirson - Bertin Technologies
PATCH 1/1 git-bisect.txt: example for bisecting with hotfix
In reply to Ralf WildenhuesGive an example on how to bisect when older revisions need a hotfix to build, run or test. Triggered by the binutils/kernel issue at
http://thread.gmane.org/gmane.comp.gnu.binutils/52601/focus=1112779
---
Maybe this doc fix would do. Just tag the hotfix and tell people to cherry-pick it like this. I don't think "git bisect --with-fix=hotfix" would be much simpler. (culling kernel list from cc - don't apply this to the wrong tree :)
Documentation/git-bisect.txt | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-)
Documentation/git-bisect.txt +11 -0
@@ -322,6 +322,17 @@ $ git bisect run sh -c "make || exit 125; ~/check_test_case.sh" + Does the same as the previous example, but on a single line. +* Bisect with compatibility hotfix: ++ +------------ +$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 +$ git bisect run sh -c "git cherry-pick -n hotfix || exit 125; make || exit 125; ~/check_test_case.sh" +------------ ++ +Does the same as the previous example, but applies an additional patch +before building. This is useful when your build or test environment changed so +that older revisions may need a fix which newer ones have already. + Author ------ Written by Linus Torvalds <[email protected]>
Signature · 1 line
1.7.4.1.404.g62d316
Re: [PATCH] git-bisect.txt: example for bisecting with hotfix
Documentation/git-bisect.txt $ git bisect run sh -c "make || exit 125; ~/check_test_case.sh" · line 335
Quoted 11 lines · Michael J Gruber
Documentation/git-bisect.txt +11
-0+* Bisect with compatibility hotfix: ++ +------------ +$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 +$ git bisect run sh -c "git cherry-pick -n hotfix || exit 125; make || exit 125; ~/check_test_case.sh" +------------ ++ +Does the same as the previous example, but applies an additional patch +before building. This is useful when your build or test environment changed so +that older revisions may need a fix which newer ones have already. +
It is a good idea to add an example that shows it is perfectly Ok to muck with the working tree before testing, but I don't see this patch as such.
First of all, doesn't bisect_checkout does its job with "checkout -q" without "-f"? How would that interact with running cherry-pick _every time_ you check commit to be tested out? In some situations it may work OK by accident, but as an example that is likely to be cut&pasted I think we should show a reasonably safer way than this.
There likely are more than one hot-fixes; it would make more sense to illustrate merging a hot-fixes branch using "git merge --no-commit" than using cherry-pick.
But the above are minor; the biggest issue I have with this patch is that it breaks the train of thought for people who are reading from top to bottom.
Look at what is there currently. It starts simple (single command run via "run" interface), and demonstrates that anything complex can be easily managed with a fully-spelled-out "one test wrapper that builds and then runs test" example, to show the most generic way you can use. It then introduces special exit codes in the script, as that form is easier to read than a single command line.
It then shows, as a final aside, that it isn't strictly required to use a wrapper script and you could use "sh -c" to wrap that in the command line, which may be easier to use when (and only when IMO---if you will have anything that needs debugging then you are better off with the first approach) the command line you use for testing is trivial.
I think a new example you are adding would fit much better in the flow if you replaced the example it refers to as "the previous example". There are that "previous example" that uses the "check_test_case.sh", and the one before that one that uses "make test"; they are duplicates that do not add much value and we would add value by dropping one of them. It probably is better to remove the "make test" one and keep the "check_test_case.sh" one, as long as you explain "check_test_case.sh" sufficiently well, because the latter is more generally applicable.
The new example would fit well as an illustration of what you _could_ have in test.sh script when you need to do more elaborate set-up before testing each revision, e.g., you tweak the working tree with hotfix before running "make || exit 125", and clean that up after you tested. The core of the new section would look like this:
$ cat test.sh #!/bin/sh
# tweak the working tree by merging the hot-fix branch
# and then attempt a build
if git cherry-pick --no-commit hot-fix &&
make
then
# run project specific test and report its status
./test.sh
status=$?
else
# tell the caller this is untestable
status=125
fi # undo the tweak to allow clean flipping to the next commit
git reset --hard# return control exit $status
Re: [PATCH] Document 'git bisect fix'.
In reply to Ralf WildenhuesHi,
Quoted 4 lines · Ralf Wildenhues
git bisect is sometimes less effective than it could be in projects with long-lived but simple bugs (e.g., little-tested configurations). Rather than skipping vast revision ranges, it might be easier to fix them up from known bugfix branches.
It's already possible to deal with this problem by creating a new branch where the bug is fixed, and then using "git replace", so that the new branch is used instead of the old one.
Please search for "git replace" in this doc:
http://www.kernel.org/pub/software/scm/git/docs/git-bisect-lk2009.html
Quoted 3 lines
'git bisect fix' teaches bisect about when some known bug was introduced and when it was fixed, so that bisect can merge in the fix when needed into new test candidates.
Perhaps some people would find it easier to use what you suggest but using git replace may be nicer because you have to create the new branch once, so you need to fix merge or rebase problems only once. And the new branch may be useful not only for bisecting, for example to recreate old versions.
Thanks,
Christian.
Re: [PATCH] Document 'git bisect fix'.
Christian Couder venit, vidit, dixit 16.03.2011 10:52:
Quoted 20 lines
Hi,
Quoted 4 lines · Ralf Wildenhues
git bisect is sometimes less effective than it could be in projects with long-lived but simple bugs (e.g., little-tested configurations). Rather than skipping vast revision ranges, it might be easier to fix them up from known bugfix branches.
It's already possible to deal with this problem by creating a new branch where the bug is fixed, and then using "git replace", so that the new branch is used instead of the old one.
Please search for "git replace" in this doc:http://www.kernel.org/pub/software/scm/git/docs/git-bisect-lk2009.html
Quoted 3 lines
'git bisect fix' teaches bisect about when some known bug was introduced and when it was fixed, so that bisect can merge in the fix when needed into new test candidates.
Quoted 5 lines
Perhaps some people would find it easier to use what you suggest but using git replace may be nicer because you have to create the new branch once, so you need to fix merge or rebase problems only once. And the new branch may be useful not only for bisecting, for example to recreate old versions.
I'd say the replace method is perfect for transporting an existing fix "back in time" when the range of non-bisectable commits is limited. But since you have to replace the right (most recent) commit in that range it is less convenient when you have a fix due to a changed/exotic build environment or such which you do not want in your mainline.
Also, you have to rebase the whole history back to the commit which introduced the problem - and that could be the root commit if the bisect problems arise from a changed toolchain, like here.
MichaelP.S.: Did you cull cc on purpose or did gmane mess up? Readding AM, LT, TG
Re: [PATCH] Document 'git bisect fix'.
Quoted 10 lines · Michael J Gruber
Christian Couder venit, vidit, dixit 16.03.2011 10:52:
...Quoted 2 lines
It's already possible to deal with this problem by creating a new branch where the bug is fixed,...
I'd say the replace method is perfect for transporting an existing fix "back in time" when the range of non-bisectable commits is limited. But since you have to replace the right (most recent) commit in that range it is less convenient when you have a fix due to a changed/exotic build environment or such which you do not want in your mainline.
I totally agree with Michael. If somebody has _already_ used "replace" to make an alternate history in which nobody made any mistake by masking each and every bug fixed in the past, your bisect would be easier, but that is nothing more than a theoretical daydreaming. Who in the right mind would do that?
If you need fixes applied for unrelated bug to even trigger the bug you are chasing, "replace" is not a practical option. You might even be the first to notice that these "known fixes" mattered in the part of the history you happen to be bisecting, and nobody sane would have prepared such "replace" in the past just in case.
Treat "replace" as nothing more than a reimplementation of "grafts" done right (i.e. can be transferred using the usual git transfer protocols); I don't want to see its use advocated for applications it is not suited. It just confuses people.
PATCH v2 1/2 git-bisect.txt: streamline run presentation
In reply to Junio C HamanoStreamline the presentation of "bisect run" by removing one example which does not introduce new concepts.
--- Documentation/git-bisect.txt | 34 ++++++++-------------------------- 1 files changed, 8 insertions(+), 26 deletions(-)
Documentation/git-bisect.txt +8 -26
@@ -274,53 +274,35 @@ $ git bisect start HEAD origin -- # HEAD is bad, origin is good $ git bisect run make test # "make test" builds and tests ------------ -* Automatically bisect a broken test suite: -+ ------------- -$ cat ~/test.sh -#!/bin/sh -make || exit 125 # this skips broken builds -make test # "make test" runs the test suite -$ git bisect start v1.3 v1.1 -- # v1.3 is bad, v1.1 is good -$ git bisect run ~/test.sh ------------- -+ -Here we use a "test.sh" custom script. In this script, if "make" -fails, we skip the current commit. -+ -It is safer to use a custom script outside the repository to prevent -interactions between the bisect, make and test processes and the -script. -+ -"make test" should "exit 0", if the test suite passes, and -"exit 1" otherwise. - * Automatically bisect a broken test case: + ------------ $ cat ~/test.sh #!/bin/sh make || exit 125 # this skips broken builds -~/check_test_case.sh # does the test case passes ? +~/check_test_case.sh # does the test case pass? $ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 $ git bisect run ~/test.sh ------------ + -Here "check_test_case.sh" should "exit 0" if the test case passes, +Here we use a "test.sh" custom script. In this script, if "make" +fails, we skip the current commit. +"check_test_case.sh" should "exit 0" if the test case passes, and "exit 1" otherwise. + -It is safer if both "test.sh" and "check_test_case.sh" scripts are +It is safer if both "test.sh" and "check_test_case.sh" are outside the repository to prevent interactions between the bisect, make and test processes and the scripts. -* Automatically bisect a broken test suite: +* Automatically bisect a broken test case: + ------------ $ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 $ git bisect run sh -c "make || exit 125; ~/check_test_case.sh" ------------ + -Does the same as the previous example, but on a single line. +This shows that you can do without a run script if you write the test +on a single line. Author ------
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1.7.4.1.404.g62d316
PATCH v2 2/2 git-bisect.txt: example for bisecting with hot-fix
In reply to Junio C HamanoGive an example on how to bisect when older revisions need a hot-fix to build, run or test. Triggered by the binutils/kernel issue at
http://thread.gmane.org/gmane.comp.gnu.binutils/52601/focus=1112779
---
The example script is basically Junio's, with merge rather than cherry-pick.
Documentation/git-bisect.txt | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-)
Documentation/git-bisect.txt +33 -0
@@ -294,6 +294,39 @@ It is safer if both "test.sh" and "check_test_case.sh" are outside the repository to prevent interactions between the bisect, make and test processes and the scripts. +* Automatically bisect with temporary modifications (hot-fix): ++ +------------ +$ cat ~/test.sh +#!/bin/sh + +# tweak the working tree by merging the hot-fix branch +# and then attempt a build +if git merge --no-commit hot-fix && + make +then + # run project specific test and report its status + ~/check_test_case.sh + status=$? +else + # tell the caller this is untestable + status=125 +fi + +# undo the tweak to allow clean flipping to the next commit +git reset --hard + +# return control +exit $status +------------ ++ +This applies modifications from a hot-fix branch before each test run, +e.g. in case your build or test environment changed so that older +revisions may need a fix which newer ones have already. (Make sure the +hot-fix branch is based off a commit which is contained in all revisions +which you are bisecting, so that the merge does not pull in too much, or +use `git cherry-pick` instead of `git merge`.) + * Automatically bisect a broken test case: + ------------
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