Re: [syslinux] Etherboot and gpxe

On Tue, Aug 4, 2009 at 11:50 AM, Stefan Hajnoczi<[email protected]> wrote:
> On Tue, Aug 4, 2009 at 7:31 PM, Joshua Oreman<[email protected]> wrote:
>> I have seen this infinite-looping on dependencies behavior when I've
>> #included a nonexistent header file in one of my source files. You may
>> want to check for that.
> Sounds like something that would be worth fixing.

It would be if I could reproduce it. :-) I tried to replicate the
situation that made me notice this (#include "debug.h" in several
ath5k sources) and it only did the dependencies twice. If the problem
really is due to this, there's probably another subtle factor I
haven't noticed.

Most likely it's something to do with the fact that gcc's Makefile
rule generator will cheerfully generate dependencies on nonexistent
includes. gPXE's build system (sensibly) makes the .d Makefile
fragment file depend on all its source file's dependencies, and make
will consider a rule depending on a nonexistent non-.PHONY target as
always in need of remaking. Since the .d Makefile fragments are
`include'd, they are subject to make's Makefile-remaking logic, which
restarts the make if any Makefiles are updated. When it restarts, it
rereads all the Makefiles and rules thereabout, and sees again the
dependency on a nonexistent file that forces remaking... ad infinitum.

There may be a make version dependency in here, since I have upgraded
my system since I noticed this behavior. I'm running GNU Make 3.81 (as
told by make -v); Joyce, which are you running? I would consider this
more a bug in make than in gPXE's use of it, and it may have been
fixed by upstream.

-- Josh

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