prefix and python site-packages

prefix and python site-packages

[Olaf Hering]

configure --prefix=/some/where puts pygrub and xen/lowlevel/xc.so below
/some/where. But pygrub fails because it can not find the python
site-packages. Is there a clean way to automate something like this?

diff --git a/tools/pygrub/src/pygrub b/tools/pygrub/src/pygrub
index 7759b1a..4134082 100644
--- a/tools/pygrub/src/pygrub
+++ b/tools/pygrub/src/pygrub
@@ -14,6 +14,7 @@
 #
 
 import os, sys, string, struct, tempfile, re, traceback
+sys.path.insert(0, "/some/where/lib64/python2.6/site-packages")
 import errno
 import copy
 import logging


Olaf

Re: prefix and python site-packages

[Ian Campbell]

On Wed, 2014-04-23 at 10:21 +0200, Olaf Hering wrote:
> configure --prefix=/some/where puts pygrub and xen/lowlevel/xc.so below
> /some/where. But pygrub fails because it can not find the python
> site-packages. Is there a clean way to automate something like this?

Is this https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=693721 ? I
suppose not quite.

I think if you are installing to a non-standard prefix then you might
expect to need to take manual action, like
editing /etc/python*/sitecustomize.py or setting $PYTHONPATH (this is
analogous to editing /etc/ld.so.conf or setting $LD_LIBRARY_PATH I
think).

I don't suppose python has an analogue of -rpath?

Ian.

Re: prefix and python site-packages

[Olaf Hering]

On Wed, Apr 23, Ian Campbell wrote:

> I don't suppose python has an analogue of -rpath?

Looks like sys.path.insert() is the python way of rpath. 
Would it be acceptable to tweak pygrub at install time and insert
something like the hack I had posted earlier? From what I have seen
pygrub is the only remaining binary using the xen.lowlevel stuff.

Olaf

Re: prefix and python site-packages

[Ian Campbell]

On Wed, 2014-04-23 at 11:33 +0200, Olaf Hering wrote:
> On Wed, Apr 23, Ian Campbell wrote:
> 
> > I don't suppose python has an analogue of -rpath?
> 
> Looks like sys.path.insert() is the python way of rpath. 
> Would it be acceptable to tweak pygrub at install time and insert
> something like the hack I had posted earlier?

Does Python distutils (used by tools/pygrub/setup.py) not have any
support for doing this sort of thing automatically?

>  From what I have seen
> pygrub is the only remaining binary using the xen.lowlevel stuff.

It only uses it to decide if the hypervisor supports 64 bit PV guests.
Since the we no longer have a 32-bit hypervisor perhaps we can just nuke
that check and sidestep the whole problem?

Ian.

Re: prefix and python site-packages

[Olaf Hering]

On Wed, Apr 23, Ian Campbell wrote:

> On Wed, 2014-04-23 at 11:33 +0200, Olaf Hering wrote:
> > On Wed, Apr 23, Ian Campbell wrote:
> > 
> > > I don't suppose python has an analogue of -rpath?
> > 
> > Looks like sys.path.insert() is the python way of rpath. 
> > Would it be acceptable to tweak pygrub at install time and insert
> > something like the hack I had posted earlier?
> 
> Does Python distutils (used by tools/pygrub/setup.py) not have any
> support for doing this sort of thing automatically?

I have to check.
But how would pygrub, or any other helloworld.py, know that it was
installed into --prefix= and its libs/modules are also in --prefix=? I
think something has to be hardcoded, unless PYTHONPATH or simimar is
used to point to a specific --prefix=.

> >  From what I have seen
> > pygrub is the only remaining binary using the xen.lowlevel stuff.
> 
> It only uses it to decide if the hypervisor supports 64 bit PV guests.
> Since the we no longer have a 32-bit hypervisor perhaps we can just nuke
> that check and sidestep the whole problem?

It also uses fsimage and grub.*, which is also installed below --prefix=

Olaf

Re: prefix and python site-packages

[Ian Campbell]

On Wed, 2014-04-23 at 12:05 +0200, Olaf Hering wrote:
> On Wed, Apr 23, Ian Campbell wrote:
> 
> > On Wed, 2014-04-23 at 11:33 +0200, Olaf Hering wrote:
> > > On Wed, Apr 23, Ian Campbell wrote:
> > > 
> > > > I don't suppose python has an analogue of -rpath?
> > > 
> > > Looks like sys.path.insert() is the python way of rpath. 
> > > Would it be acceptable to tweak pygrub at install time and insert
> > > something like the hack I had posted earlier?
> > 
> > Does Python distutils (used by tools/pygrub/setup.py) not have any
> > support for doing this sort of thing automatically?
> 
> I have to check.
> But how would pygrub, or any other helloworld.py, know that it was
> installed into --prefix= and its libs/modules are also in --prefix=? I
> think something has to be hardcoded, unless PYTHONPATH or simimar is
> used to point to a specific --prefix=.

setuyp.py is the thing which does all of this installing, so it knows
where everything is going. It presumably also knows the default python
path.

How does this work for every other python library/application out there?
I can't imagine we are special here.

> > >  From what I have seen
> > > pygrub is the only remaining binary using the xen.lowlevel stuff.
> > 
> > It only uses it to decide if the hypervisor supports 64 bit PV guests.
> > Since the we no longer have a 32-bit hypervisor perhaps we can just nuke
> > that check and sidestep the whole problem?
> 
> It also uses fsimage and grub.*, which is also installed below --prefix=

OK, I only looked at xen.lowlevel since that was what you mentioned.

Ian.

Re: prefix and python site-packages

[Ian Jackson]

Olaf Hering writes ("prefix and python site-packages"):
> configure --prefix=/some/where puts pygrub and xen/lowlevel/xc.so below
> /some/where. But pygrub fails because it can not find the python
> site-packages. Is there a clean way to automate something like this?

I think normally --prefix should refer to somewhere where your python
will look for packages.

If it doesn't, computing the correct path to use is going to be
complicated I think.

Ian.