Re: [Qemu-devel] [PULL 7/7] tcg-i386: Use new return-argument ld/st helpers

[Stefan Weil]

Am 28.05.2014 19:21, schrieb Stefan Weil:
> Am 28.05.2014 19:12, schrieb Richard Henderson:
>> On 05/27/2014 03:37 PM, Stefan Weil wrote:
>>> Hi Richard,
>>>
>>> this patch has broken the 64 bit version of QEMU for Windows: a Linux
>>> guest starts booting, but hangs after "Booting the kernel.". I got a bug
>>> report from a user and did a "git bisect" with a Tiny Core Linux guest /
>>> cross build with default options / cross test with wine64 and default
>>> options. Git reported this commit:
>>>
>>> 401c227b0a1134245ec61c6c5a9997cfc963c8e4 is the first bad commit
>>> commit 401c227b0a1134245ec61c6c5a9997cfc963c8e4
>>> Author: Richard Henderson <address@hidden>
>>> Date:   Thu Jul 25 07:16:52 2013 -1000
>>>
>>>     tcg-i386: Use new return-argument ld/st helpers
>>>    
>>>     Discontinue the jump-around-jump-to-jump scheme, trading it for a single
>>>     immediate move instruction.  The two extra jumps always consume 7 bytes,
>>>     whereas the immediate move is either 5 or 7 bytes depending on where the
>>>     code_gen_buffer gets located.
>>>    
>>>     Signed-off-by: Richard Henderson <address@hidden>
>>>
>>> :040000 040000 dfd9a66c85713cd1886a3342de1e9ac95d7ea43f
>>> df8673dea69bc89cc2cc979aa24415e3fea4ed53 M    include
>>> :040000 040000 1f7cd5291f2c69b4126c63bd567c6b106eb332c9
>>> 87e7ece766168dda860b513dc97fe5af28ec2c4b M    tcg
>>>
>>> 32 bit versions of QEMU for Windows don't show this problem.
>>
>> I'm having problem booting any iso with wine at the moment:
>>
>> $ wine64 ./x86_64-softmmu/qemu-system-x86_64.exe -L ./pc-bios \
>>     -vnc :1 -cdrom ../../../Downloads/TinyCore-current.iso
>> Assertion failed!
>>
>> Program: Z:\home\rth\work\qemu\bld-w64\x86_64-softmmu\qemu-system-x86_64.exe
>> File: /home/rth/work/qemu/qemu/qemu-coroutine-lock.c, Line 91
>>
>> Expression: qemu_in_coroutine()
>>
>> abnormal program termination
>>
>> Naturally, this isn't happening with a native linux boot with the same 
>> arguments.
>>
>> But I can boot an alpha rom:
>>
>> $ wine64 ./alpha-softmmu/qemu-system-alpha.exe -L ./pc-bios/ -nographic
>> PCI: 00:00:0 class 0300 id 1013:00b8
>> PCI:   region 0: 10000000
>> PCI:   region 1: 12000000
>> PCI: 00:01:0 class 0200 id 8086:100e
>> PCI:   region 0: 12020000
>> PCI:   region 1: 0000c000
>> PCI: 00:02:0 class 0101 id 1095:0646
>> PCI:   region 0: 0000c040
>> PCI:   region 1: 0000c048
>> PCI:   region 3: 0000c04c
>>>>>
>>
>> Which says to me that it's rather unlikely that this basic load/store patch
>> could be the problem.


Well, git bisect found it, and it definitely makes a difference whether
this patch is applied or not.

Typical problems with w64 are pointer / long size (pointers are 8 byte,
long integers are only 4 byte) or calling conventions (they differ from
w32 or Linux). See
https://en.wikipedia.org/wiki/X86_calling_conventions#Microsoft_x64_calling_convention
or http://msdn.microsoft.com/en-us/library/ms235286.aspx.

Stefan