Re: [libvirt] [PATCH] build: Fix build with old automake

On Tue, Mar 18, 2014 at 06:27:48 -0600, Eric Blake wrote: > On 03/18/2014 05:00 AM, Jiri Denemark wrote: > >>> Why don't we just avoid the whole issue by removing use of abs_srcdir >>> and abs_builddir. Can this rule: >>> >>> $(abs_builddir)/cpu/cpu_map.xml: >>> $(AM_V_GEN)ln -s $(abs_srcdir)/cpu/cpu_map.xml $@ >>> >>> be just changed to >>> >>> cpu/cpu_map.xml: >>> $(AM_V_GEN)ln -s $(srcdir)/cpu/cpu_map.xml $@ >> >> That's what I tried first but it does not work at all. I don't >> understand why but make thinks cpu/cpu_map.xml target is uptodate even >> though the file does not exist in builddir. > > That would be VPATH rewriting at play. Does $(builddir)/cpu/cpu_map.xml > fare any better? No, that doesn't work either. ... > But maybe that's some food for thought - instead of having a rule that > uses a direct file name, perhaps you can instead have a witness rule on > a stamp file name, where we write the link ourselves when needed, and > then have all dependencies be on the stamp (which will ALWAYS exist only > in builddir): > > cpu/cpu_map.xml.stamp: > $(AM_V_GEN)if test -f cpu/cpu_map.xml; then \ > :; else \ > ln -s `cd $(srcdir) && pwd`/cpu/cpu_map.xml \ > cpu/cpu_map.xml; \ > fi && touch $@ OK, this seems to work. It's uglier and doesn't regenerate the link if someone removes it (the *.stamp file would need to be removed too) but if that's considered a better way compared to setting abs_*dir, I can make a proper patch out of it after testing it in all situations.