[issue7201] double Endian problem and more on arm
Mark Dickinson dicki...@gmail.com added the comment: won't fix seems reasonable to me. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Changes by Mark Dickinson dicki...@gmail.com: -- status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Meador Inge mead...@gmail.com added the comment: I think Mark's original pointer to issue1762561 was right on. The last two cases are failing due to the mixed-endian format (mentioned in that issue) used in OABI. You can see this in the output of 'test_endian_double': '182D4454FB210940' != 'FB210940182D4454' Note that the values are the same except the two 32-bit words are swapped. Similarly, in 'test_unaligned_native_struct_fields': '123412007856341200B81E09401F85EB51' != '1234120078563412001F85EB51B81E0940' The first 8 bytes in each case are the same. The last 8 bytes of each (which represent floating-point doubles) are the same except, again, the words are swapped. I am going to close this out as won't fix. As mentioned in issue1762561, supporting OABI will involve taking on another host platform. EABI is surely more predominant these days anyway. -- resolution: - wont fix stage: - committed/rejected type: - behavior ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Meador Inge mead...@gmail.com added the comment:
OK, I got an OABI system setup. I am seeing the 'test_struct_return_2H'
failure, which actually segfaults in my setup. The difference does,
indeed, seem like an ABI mismatch.
The test code that is failing has a Python side like:
def test_struct_return_2H(self):
class S2H(Structure):
_fields_ = [(x, c_short),
(y, c_short)]
dll.ret_2h_func.restype = S2H
dll.ret_2h_func.argtypes = [S2H]
inp = S2H(99, 88)
s2h = dll.ret_2h_func(inp)
self.assertEqual((s2h.x, s2h.y), (99*2, 88*3))
and a C code side that looks like:
typedef struct {
short x;
short y;
} S2H;
S2H ret_2h_func(S2H inp)
{
inp.x *= 2;
inp.y *= 3;
return inp;
}
The APCS Section 5.4 Result Return [1], says:
A Composite Type not larger than 4 bytes is returned in r0. The format
is as if the result had been stored in memory at a word-aligned address
and then loaded into r0 with an LDR instruction. Any bits in r0 that
lie outside the bounds of the result have unspecified values.
The EABI implementation does exactly this and packs the structure into r0,
where as the OABI implementation places the address of a structure in r0.
'ctypes' is assuming the former and on an OABI system the contents of r0 are
treated as an address, where they are actually a value. Boom goes the dynamite.
I am looking into 'test_endian_double' and
'test_unaligned_native_struct_fields' now.
[1] http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf
--
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue7201
___
___
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Meador Inge mead...@gmail.com added the comment: The 'test_endian_double' test fails because the 'double' floating-point type for an interpreter built for OABI is unknown: float.__getformat__(float) 'IEEE, little-endian' float.__getformat__(double) 'unknown' According to [1], the double format discrepancies seem to be expected. [1] http://wiki.debian.org/ArmEabiPort#ARM_floating_points -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Mark Dickinson dicki...@gmail.com added the comment: I don't think it is practical to support both ABIs. I suspect you're right. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Mark Dickinson dicki...@gmail.com added the comment:
I ran the ctypes tests on Debian GNU/Linux 5.0.8 (lenny) on an ARMv5tejl
Versatile kernel and everything passed.
I believe the problem is specific to machines still using the old ABI ('OABI').
Which ABI was being used on your test machine? (Not sure how to tell, but
there's more information about the ABIs at:
http://wiki.debian.org/ArmEabiPort
)
--
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue7201
___
___
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Meador Inge mead...@gmail.com added the comment:
On Mon, Sep 12, 2011 at 7:10 AM, Mark Dickinson rep...@bugs.python.org wrote:
Mark Dickinson dicki...@gmail.com added the comment:
I believe the problem is specific to machines still using the old ABI
('OABI'). Which ABI was being used on your test machine?
I tested the new ABI (armel). I will try the old ABI. However, after
reading over the ABI differences, the problems seem to be expected.
In particular:
Struct packing and alignment
With the new ABI, default structure packing changes, as do some
default data sizes and alignment (which also have a knock-on effect on
structure packing). In particular the minimum size and alignment of a
structure was 4 bytes. Under the EABI there is no minimum and the
alignment is determined by the types of the components it contains.
This will break programs that know too much about the way structures
are packed and can break code that writes binary files by dumping and
reading structures.
Once I get an OABI system up and running I will substantiate that
claim. I don't think there is going to be a bug fix here as I don't
think it is practical to support both ABIs. Just a these tests are
expected to fail due to ABI differences x, y, z kind of thing.
--
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue7201
___
___
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Meador Inge mead...@gmail.com added the comment: I ran the ctypes tests on Debian GNU/Linux 5.0.8 (lenny) on an ARMv5tejl Versatile kernel and everything passed. Is anyone else still seeing errors? -- assignee: theller - nosy: +meadori -theller ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Mark Dickinson dicki...@gmail.com added the comment: The 4th failure (test_endian_double) probably has nothing to do with ctypes. See also issue #1762561. -- nosy: +mark.dickinson ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Mancausoft b...@mancausoft.org added the comment: Mark Dickinson rep...@bugs.python.org scrisse: The 4th failure (test_endian_double) probably has nothing to do with ctypes. See also issue #1762561. I try to use the patch arm-float2.diff, but test result is the same: == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.AsParamPropertyWrapperTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.AsParamWrapperTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.BasicWrapTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_endian_double (ctypes.test.test_byteswap.Test) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_byteswap.py, line 137, in test_endian_double self.failUnlessEqual(bin(struct.pack(d, math.pi)), bin(s)) AssertionError: '182D4454FB210940' != 'FB210940182D4454' == FAIL: test_unaligned_native_struct_fields (ctypes.test.test_byteswap.Test) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_byteswap.py, line 277, in test_unaligned_native_struct_fields self.failUnlessEqual(bin(s1), bin(s2)) AssertionError: '123412007856341200B81E09401F85EB51' != '1234120078563412001F85EB51B81E0940' -- Ran 324 tests in 8.525s Mancausoft -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
Mark Dickinson dicki...@gmail.com added the comment: Hmm. Okay, I take it back then. :) Sorry for the noise. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7201] double Endian problem and more on arm
New submission from Mancausoft b...@mancausoft.org: I compile python for arm (on debian etch) but it don't pass ctype test: == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.AsParamPropertyWrapperTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.AsParamWrapperTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_struct_return_2H (ctypes.test.test_as_parameter.BasicWrapTestCase) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_as_parameter.py, line 171, in test_struct_return_2H self.failUnlessEqual((s2h.x, s2h.y), (99*2, 88*3)) AssertionError: (99, 88) != (198, 264) == FAIL: test_endian_double (ctypes.test.test_byteswap.Test) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_byteswap.py, line 137, in test_endian_double self.failUnlessEqual(bin(struct.pack(d, math.pi)), bin(s)) AssertionError: '182D4454FB210940' != 'FB210940182D4454' == FAIL: test_unaligned_native_struct_fields (ctypes.test.test_byteswap.Test) -- Traceback (most recent call last): File /mnt/root/stackless-2.6.3/Lib/ctypes/test/test_byteswap.py, line 277, in test_unaligned_native_struct_fields self.failUnlessEqual(bin(s1), bin(s2)) AssertionError: '123412007856341200B81E09401F85EB51' != '1234120078563412001F85EB51B81E0940' -- assignee: theller components: ctypes messages: 9 nosy: mancausoft, theller severity: normal status: open title: double Endian problem and more on arm versions: Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
