On Tue, Mar 18, 2014 at 10:42:01 +0000, Daniel Berrange wrote:
On Tue, Mar 18, 2014 at 11:36:51AM +0100, Jiri Denemark wrote:
On Mon, Mar 17, 2014 at 09:33:11 -0600, Eric Blake wrote:
On 03/14/2014 12:55 PM, Jiri Denemark wrote:
On Fri, Mar 14, 2014 at 07:54:58 -0600, Eric Blake wrote:
On 03/14/2014 04:43 AM, Jiri Denemark wrote:
Ancient automake (such as from RHEL5) does not provide abs_srcdir and abs_builddir variables which are used by a recent commit of mine (e562e82).
Signed-off-by: Jiri Denemark <jdenemar@redhat.com> ---
+# old automake does not provide abs_{src,build}dir variables +abs_builddir = $(shell pwd) +abs_srcdir = $(shell cd $(srcdir) && pwd)
Hmm, just noticed another thing - with NEWER automake, we are now less efficient (calling out to $(shell) overwrites the value that is already provided for free without a subprocess by newer automake). Does it work if you use:
abs_builddir ?= $(shell pwd)
Automake does a fair amount of magic here so abs_builddir = $(shel ...) does not actually overwrite the old value because there is no old value :-) Automake just does not put it's own abs_builddir definition in that case. If I switch to abs_builddir ?= $(shell ...), automake adds it's own definition so it seems it could work except that it doesn't. With "=", automake adds the definition above the other variable definition and namely above libvirt_cpu_la_DEPENDENCIES which uses it:
abs_builddir = $(shell ...) ... libvirt_cpu_la_DEPENDENCIES = $(abs_builddir)/... ... rules
When I switch to "?=", automake apparently does not recognize it as a variable definition and puts it between the block with variable definitions and rules. Thus the result is:
abs_builddir = /some/build/path ... libvirt_cpu_la_DEPENDENCIES = $(abs_builddir)/... ... abs_builddir ?= $(shell ...) ... rules
which of course does not work with old automake which does not add the first abs_builddir definition there and thus libvirt_cpu_la_DEPENDENCIES sees $(abs_builddir) empty.
Anyway, making two extra shell commands once per build does not seem like anything we should really care about so I'd just stick with
abs_builddir = $(shell ...)
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. And $(srcdir) doesn't work for relative VPATH. For example, if VPATH is .., then abs_srcdir = /some/path/src abs_builddir = /some/path/build/src srcdir = ../../src and the /some/path/build/src/cpu/cpu_map.xml link will be ../../src/cpu/cpu_map.xml and thus will point to itself. And we can't just blindly do ln -s ../$(srcdir)/cpu/cpu_map.xml $@ because this would not work for absolute VPATH, when srcdir is /some/path/src. Yeah, it's a mess. Jirka