Re: [Xen-devel] [PATCH] xen/tools: support Python 2 and Python 3

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/02/18 05:52, Doug Goldstein wrote:

These changes should make it possible to support modern Pythons as well
as the oldest Python 2 still supported.

Signed-off-by: Doug Goldstein <cardoe@xxxxxxxxxx>

To the overall effect, this is definitely a good thing.  Some queries however...

---
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/tools/compat-build-header.py |  2 +-
 xen/tools/compat-build-source.py |  2 +-
 xen/tools/gen-cpuid.py           | 37 +++++++++++++++++++++++++++----------
 xen/tools/get-fields.sh          |  2 +-
 4 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/xen/tools/compat-build-header.py b/xen/tools/compat-build-header.py
index 32421b645b..546371225d 100755
--- a/xen/tools/compat-build-header.py
+++ b/xen/tools/compat-build-header.py
@@ -23,4 +23,4 @@ pats = [
 for line in sys.stdin.readlines():
     for pat in pats:
         line = re.subn(pat[0], pat[1], line)[0]
-    print line.rstrip()
+    sys.stdout.write(line.rstrip() + '\n')

Is there anything wrong with print(line.rstrip()) which is the more common way of doing this?

diff --git a/xen/tools/compat-build-source.py b/xen/tools/compat-build-source.py
index 595bc3ff58..8101290ebe 100755
--- a/xen/tools/compat-build-source.py
+++ b/xen/tools/compat-build-source.py
@@ -26,4 +26,4 @@ for pat in pats:
 for line in sys.stdin.readlines():
     for pat in pats:
         line = re.sub(pat[0], pat[1], line)
-    print line.rstrip()
+    sys.stdout.write(line.rstrip() + '\n')
diff --git a/xen/tools/gen-cpuid.py b/xen/tools/gen-cpuid.py
index 613b909c3d..d64f257816 100755
--- a/xen/tools/gen-cpuid.py
+++ b/xen/tools/gen-cpuid.py
@@ -3,6 +3,13 @@
 
 import sys, os, re
 
+if (sys.version_info > (3, 0)):
+    def long(x):
+        return x

Strictly speaking, return int(x), however...

+
+    def xrange(x):
+        return range(x)
+
 class Fail(Exception):
     pass
 
@@ -98,13 +105,13 @@ def parse_definitions(state):
 def featureset_to_uint32s(fs, nr):
     """ Represent a featureset as a list of C-compatible uint32_t's """
 
-    bitmap = 0L
+    bitmap = long(0)
     for f in fs:
-        bitmap |= 1L << f
+        bitmap |= long(1) << f

Having tested this out, I think the L suffixes can just be dropped:

Python 2.4.3 (#1, Sep 21 2011, 20:06:00)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-51)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> bitmap = 0
>>> type(bitmap)
<type 'int'>
>>> for x in xrange(80): bitmap |= 1 << x
...
>>> type(bitmap)
<type 'long'>
>>>

I don't recall why I wrote it like this, but I don't think its necessary.  As a result, you shouldn't need to define long above.

~Andrew

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