On 18.10.2021 11:51, Anthony PERARD wrote: > On Mon, Oct 18, 2021 at 11:02:20AM +0200, Jan Beulich wrote: >> On 15.10.2021 18:58, Anthony PERARD wrote: >>> On Thu, Oct 14, 2021 at 12:14:29PM +0200, Jan Beulich wrote: >>>> On 24.08.2021 12:50, Anthony PERARD wrote: >>>>> --- a/xen/Rules.mk >>>>> +++ b/xen/Rules.mk >>>>> @@ -38,7 +38,7 @@ SPECIAL_DATA_SECTIONS := rodata $(foreach a,1 2 4 8 16, >>>>> \ >>>>> $(foreach r,rel rel.ro,data.$(r).local) >>>>> >>>>> # The filename build.mk has precedence over Makefile >>>>> -mk-dir := $(src) >>>>> +mk-dir := $(srctree)/$(src) >>>>> include $(if $(wildcard >>>>> $(mk-dir)/build.mk),$(mk-dir)/build.mk,$(mk-dir)/Makefile) >>>> >>>> Perhaps already when it was changed to $(src) the name has become >>>> slightly misleading, at least imo: I would rather expect a variable >>>> with this name to refer to the build dir/tree. Maybe "srcdir" or >>>> even shorted "sd" right from the start? (Reaching here I can finally >>>> see why having a shorthand is helpful.) >>> >>> I have to think about that. I've made some further progress in order to >>> be able to build the Xen pvhshim without a link farm and notice that >>> nearly every source file needs to use "$(srctree)/$(src)" >> >> Oh, now I'm curious as to the why here. I thought use of $(srctree) >> ought to be the exception. > > In Linux, the use of $(srctree) is indeed the exception. This is because > we have VPATH=$(srctree), so when `make` look for a prerequisite or a > target it will look first in the current directory and then in > $(srctree). That works fine as long as the source tree only have sources > and no built files. > > But if we want to be able to build the pv-shim without the linkfarm and > thus using out-of-tree build, we are going to need the ability to build > from a non-clean source tree. I don't think another way is possible. > > This can be done by teaching make to only look for source file in > $(srctree), and to look for generated/built file only in $(objtree). > That's mostly done by not using VPATH and making few other adjustments.
Oh, I see. That's ugly. Just like in Linux I was expecting that we'd do/support only in-tree or only out-of-tree builds, but not a mix of both within the same tree. But I can see how this would get in the way of a build of everything from tree root (something I personally have never made use of). Jan
