Re: [Qemu-ppc] qtest tmp105-test endianness issue

[Alexander Graf]

Am 26.01.2013 um 23:51 schrieb Andreas Färber <address@hidden>:

> Am 26.01.2013 23:21, schrieb Alexander Graf:
>> 
>> On 26.01.2013, at 23:12, Andreas Färber wrote:
>> 
>>> I've found that my tmp105-test fails on Mac OS X ppc(64), i.e. Little
>>> Endian arm-softmmu target and Big Endian host:
>>> 
>>> GTESTER check-qtest-arm
>>> mipid_reset: Display off
>>> **
>>> ERROR:/Users/andreas/QEMU/qemu/tests/libi2c-imap.c:163:omap_i2c_create:
>>> assertion failed (data == 0x34): (0x00003400 == 0x00000034)
>>> 
>>> The only other test case that uses memread() is m48t59-test, which uses
>>> size 1 MMIO accesses only. This suggests that Big Endian guest (e.g.,
>>> sparc) and Little Endian host (e.g., x86_64) may cause issues, too.
>>> 
>>> What is the expected way to handle endianness in qtest? Should
>>> qtest.c:qtest_process_command() be changed? libqtest.c:qtest_memread()?
>>> Or the test itself byteswap and, if so, under which circumstances?
>> 
>> Well, first of all qtest works on behalf of the emulated CPU. The MMIO code 
>> path doesn't care about target CPU endianness. It simply passes the "native" 
>> value to the handler. The handler however might change byte order depending 
>> on the memory api endianness flag.
>> 
>> But in this particular case, I'd be very surprised if any endianness 
>> swapping had to be involved.
> 
> Fact is, it passes on x86 and fails on ppc. :)
> Reproducible on openSUSE ppc64.

Oh, I'm sure the bug exists. What I'msaying is that nothing _should_ convert 
endianness.


Alex

> 
> Andreas
> 
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