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Subject: Re: [PATCH v3 2/2] selftests/powerpc: Add a test of the
 switch_endian() syscall
From: Michael Ellerman <mpe@ellerman.id.au>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Date: Wed, 18 Mar 2015 16:04:19 +1100
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On Tue, 2015-03-17 at 11:35 +0530, Anshuman Khandual wrote:
> On 03/17/2015 04:34 AM, Michael Ellerman wrote:
> > What are you seeing exactly?
> 
> I am running on a BE PKVM guest but compiling the test case on
> a different BE machine which has newer version of the compiler.
> 
> cc (GCC) 4.8.3 20140624
> 
> cc -O2 -Wall -g -nostdlib -m64   -c -o check.o check.S
> objcopy -j .text --reverse-bytes=4 -O binary check.o check-reversed.o
> hexdump -v -e '/1 ".byte 0x%02X\n"' check-reversed.o > check-reversed.S
> cc -O2 -Wall -g -nostdlib -m64    switch_endian_test.S check-reversed.S   -o switch_endian_test
> 
> which looks very similar to the details you have provided above.
> Running on guest or host should not make any difference.

No it shouldn't.

Can you try strace, that should give you the full result code.

Also can you try gdb. You can't breakpoint in the wrong-endian region, but it
looks like you're getting through that anyway.

So try setting a breakpoint at line ~77, and you should be back in BE. Then you
can single step and see where it errors out.

> BTW, we need to add one .gitignore file to this new test directory.

Oh yeah, thanks for the reminder.

cheers