Re: [Qemu-devel] [PATCH 1/5] target-tile: Firstly add to qemu with minimized features

[Chen Gang S <gang.chen@sunrus.com.cn>]

On 2/17/15 10:48, Chen Gang S wrote:
> On 2/17/15 08:11, Chris Metcalf wrote:
>> On 2/16/2015 6:46 PM, Peter Maydell wrote:
>>> On 17 February 2015 at 08:08, Chen Gang S <gang.chen@sunrus.com.cn> wrote:
>>>> On 2/16/15 23:24, Max Filippov wrote:
>>>>> Disassembler is not a crucial part of QEMU target.
>>>> For me, it is necessary. We need disassemble target binary instructions
>>>> (recognize them), then translate them into tcg instructions which are
>>>> grouped by Translate Block.
>>> No, Max is correct. What QEMU calls the "disassembler" is just
>>> used for debug logging: it is code that goes from target binary
>>> instructions to printed display of assembly language instructions.
>>> This is completely separate code from the code in target-*/translate.c
>>> which decodes target binary instructions and emits TCG opcodes.
>>> That code is generally called the translator or the decoder, and
>>> it is always written from scratch specifically for QEMU. Don't
>>> try to reuse code from binutils there.
>>
>> The kernel disassembly that Chen Gang is looking at is basically just an
>> instruction recognizer; it doesn't even include text strings for opcodes,
>> for example.  But my guess is that it is exactly the right starting building
>> block for decoding target binary instructions.
>>
> 
> Excuse me, I am not quite familiar with the GPL license, so I guess we
> are misunderstanding with each other.
> 
>  - it is necessary to disassemble/decode target binary instructions.
> 
>  - I want to write the decoder in translate.c according to binutils/
>    kernel disassembler (also need consider about "BFD_RELOC" and
>    "!__KERNEL__ && !__LIBC__").
> 
>  - If I reference to binutils source code, I am not quite sure whether I
>    break the license or not (is it illegal?).
> 

Originally, I really wanted to print the disassembly code, although I
knew it is optional (not necessary), just like all of you said (and
originally, I was not quite sure DISASM_ONLY, either).


Thanks.
-- 
Chen Gang

Open, share, and attitude like air, water, and life which God blessed