Messages in this thread |  | | Date | Sat, 1 Dec 2001 10:11:40 +0100 (CET) | From | willy tarreau <> | Subject | Re: Did someone try to boot 2.4.16 on a 386 ? [SOLVED] |
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> A perfect example of why having the same tree for > source and generated files and using cp -al is a > bad idea. cp -al picks up both source and > objects and you have to hope that anything that is > overwritten is hard link safe (I can tell you now > that it is not).
well, at least I only duplicate clean sources before applying a patch. So there is absolutely no shared object. It's just that when I try patches, I have about 20 source trees and it's cool to have the ability to navigate through versions without having to store 3 GB. Moreover, diff -urN is much faster this way. But it true that this is a "use at your own risk".
> kbuild 2.5 allows multiple builds from the same > source tree into separate object trees > with different configs and is safe.
Interesting, I think I'll definitely take a look at it.
> >I'll check around to see if there are other parts > >which risk to modify a file on disk without > previously > >unlink it. > > Any Makefile that does "some_command > target_file" > or runs a utility that does open(O_TRUNC) instead > of unlink(), open(O_EXCL).
there was such an example in the past with aicasm. Anyway, I think that any tool, script or Makefile that modifies the source tree and which results in a diff between the two trees after a "make distclean" is at risk because it can induce diffs between some files that can't always apply to another clean tree.
> BTW, cp -al of a pristine source tree to multiple > source trees followed by multiple compiles in > parallel is not safe either. make dep relies on > changing time stamps for include files, because > the include files are hard linked, a change in > one compile affects the other trees, with > undefined results. Also fixed in kbuild 2.5.
Never needed to do that yet.
Regards, Willy
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