Re: [Xen-devel] Hypervisor build can't work without `python` (Was: Re: Xen commit 9b0bc91b3 possibly removed too much info from README)

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Apr 17, 2019 at 12:23:29PM +0100, Andrew Cooper wrote:
> On 17/04/2019 12:16, Wei Liu wrote:
> > On Wed, Apr 17, 2019 at 12:15:04PM +0100, Andrew Cooper wrote:
> >> On 17/04/2019 12:03, Wei Liu wrote:
> >>> On Wed, Apr 17, 2019 at 11:58:49AM +0100, Andrew Cooper wrote:
> >>>> On 17/04/2019 11:57, Wei Liu wrote:
> >>>>> On Wed, Apr 17, 2019 at 11:44:36AM +0100, Andrew Cooper wrote:
> >>>>>> On 17/04/2019 11:41, Wei Liu wrote:
> >>>>>>> On Wed, Apr 17, 2019 at 10:56:57AM +0100, Wei Liu wrote:
> >>>>>>>>> Here's what i did having pulled the master at commit cb70a26
> >>>>>>>>>
> >>>>>>>>> tar xf /path/to/xen-cb70a26.tar.gz
> >>>>>>>>>
> >>>>>>>>> cd xen-master/
> >>>>>>>>>
> >>>>>>>>> PYTHON=/usr/bin/python3 ./configure --prefix=/usr   \
> >>>>>>>>>    --disable-seabios   \
> >>>>>>>>>    --disable-qemu-traditional  \
> >>>>>>>>>    --disable-rombios     \
> >>>>>>>>>    --disable-stubdom 2>&1 | tee ../config.log
> >>>>>>>>>
> >>>>>>>>> make EFI_DIR=/usr/lib/efi world 2>&1 | tee ../make_world_3.out
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> ...
> >>>>>>>>> gcc -Wp,-MD,tools/kconfig/.zconf.tab.o.d    -D_GNU_SOURCE
> >>>>>>>>> -D_DEFAULT_SOURCE -DCURSES_LOC="<ncurses.h>" -DNCURSES_WIDECHAR=1
> >>>>>>>>> -DLOCALE  -Itools/kconfig -c -o tools/kconfig/zconf.tab.o
> >>>>>>>>> tools/kconfig/zconf.tab.c
> >>>>>>>>> gcc  -o tools/kconfig/conf tools/kconfig/conf.o 
> >>>>>>>>> tools/kconfig/zconf.tab.o
> >>>>>>>>> tools/kconfig/conf -s --silentoldconfig Kconfig
> >>>>>>>>> make[3]: Leaving directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>> make -f Rules.mk _install
> >>>>>>>>> make[3]: Entering directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>> make -C tools
> >>>>>>>>> make[4]: Entering directory '/usr/src/xen/xen-master/xen/tools'
> >>>>>>>>> make symbols
> >>>>>>>>> make[5]: Entering directory '/usr/src/xen/xen-master/xen/tools'
> >>>>>>>>> gcc -Wall -Werror -Wstrict-prototypes -O2 -fomit-frame-pointer
> >>>>>>>>> -fno-strict-aliasing -Wdeclaration-after-statement -o symbols
> >>>>>>>>> symbols.c
> >>>>>>>>> make[5]: Leaving directory '/usr/src/xen/xen-master/xen/tools'
> >>>>>>>>> make[4]: Leaving directory '/usr/src/xen/xen-master/xen/tools'
> >>>>>>>>> make -f /usr/src/xen/xen-master/xen/Rules.mk include/xen/compile.h
> >>>>>>>>> make[4]: Entering directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>>  Xen 4.13-unstable
> >>>>>>>>> /bin/sh: python: command not found
> >>>>>>>>> make[4]: *** [Makefile:169: include/xen/compile.h] Error 127
> >>>>>>>> Here. The PYTHON invocation is from the hypervisor build, not the 
> >>>>>>>> tools
> >>>>>>>> build.
> >>>>>>>>
> >>>>>>>> Thanks for the log.  I will have a closer look.
> >>>>>>>>
> >>>>>>>>> make[4]: Leaving directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>> make[3]: *** [Makefile:137: /usr/src/xen/xen-master/xen/xen] Error 2
> >>>>>>>>> make[3]: Leaving directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>> make[2]: *** [Makefile:45: install] Error 2
> >>>>>>>>> make[2]: Leaving directory '/usr/src/xen/xen-master/xen'
> >>>>>>>>> make[1]: *** [Makefile:123: install-xen] Error 2
> >>>>>>>>> make[1]: Leaving directory '/usr/src/xen/xen-master'
> >>>>>>>>> make: *** [Makefile:165: world] Error 2
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> Note the
> >>>>>>>>>
> >>>>>>>>> /bin/sh: python: command not found
> >>>>>>>>>
> >>>>>>> The issue here is on LFS there is no /usr/bin/python. So the 
> >>>>>>> hypervisor
> >>>>>>> build is broken because xen/include/compile.h invokes
> >>>>>>>
> >>>>>>>  @$(PYTHON) tools/fig-to-oct.py < .banner >> $@.new
> >>>>>>>
> >>>>>>> There are other appearances of PYTHON in hypervisor build, which are
> >>>>>>> equally broken.
> >>>>>>>
> >>>>>>> We had / have a policy to avoid making hypervisor build dependent on
> >>>>>>> configure. I have CC'ed more people on their opinions.
> >>>>>> Where has $(PYTHON) got lost?  It was specified correctly to begin 
> >>>>>> with.
> >>>>> Where is it specified?
> >>>> Oh - I see now.
> >>>>
> >>>> It is specified for ./configure, but not for make.
> >>> Right.
> >>>
> >>> It works for tools because tools build includes config/Tools.mk which
> >>> contains the correct python path. Tools.mk is generated by configure.
> >>>  
> >>> Obviously hypervisor build shouldn't include Tools.mk. Furthermore, the
> >>> policy of "hv shouldn't depend on configure" makes this route a no-go.
> >>>
> >>> Either we change the policy, or we document the deficiency, or we come
> >>> up with some clever trick to probe.
> >> Given the shebang in all of our scripts, would `env python` be
> >> sufficiently clever trickery, or is that a can of worms we'd prefer not
> >> to open?
> > I already tried env python -- it didn't work. I think it searches PATHS
> > just like a shell would.
> 
> So this particular use of python is completely trivial.  It is an octal
> conversion on the banner string, to feed into a string for XEN_BANNER
> 
> It exists because I removed a fork of figlet[1] from Xen's source tree
> with this script, but its probably just as easy to do with awk or
> something similar.
> 
> ~Andrew
> 
> [1] Yes - Xen did use to carry a fork of figlet which differed solely by
> being able to output an octal-escaped string.  No - I have no words
> which can possibly be used to defend this...


But there are other less trivial ones. See xen/include/Makefile. XSM
also relies on it to generate policy. What do you want to do with those?

Wei.

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