Re: [Qemu-devel] [PATCH] translate: remove file translate-all.h

[Xuebing wang <xbing6@gmail.com>]

Hi Peter/Paolo,

Thanks for replying.

1) I am wondering if some slight refactoring (in the sense of 
superficial change of moving things around) can make 
tcg/translationblock/cpu/exec/memory/softmmu more understandable, 
especially for new engineers.

My goal is to explore the possibility of implementing tcg 
multi-threading, in a similar fashion of kvm multi-threading. It's still 
at early stage of a work-in-progress.

As I am new to qemu code base, I spent some time trying to figure out 
the design. Examples are:
-- What does exec (as in the filename of exec.c) really mean?
-- What does "all" mean as in kvm-all,c (xen-all.c, translate-all.c)? I 
assume "all" means "target independent". But, aren't other files (e.g. 
block.c, gdbstub.c) target independent?
-- What is the difference between "all" and "common" as in 
include/exec/cpu-all.h and cpu-common.h?

In my local repository, I did some refactoring. Examples are:
-- I renamed cpu-exec.c => tcg.c, to reflect the design that it's about 
one of the 3 accelerators (tcg, kvm, xen).
-- I renamed cpus.c => vcpu.c (this can be tricky). My idea of the 
object hierarchy is:
[   qom/Object                   ]
[   qdev/DeviceState         ]
[   qom/CPUState               ]
[   vcpu API (or qom/vcpu)  ]   [  CPUArchState  ]
(in the other words, I am trying to abstract/model vcpu)

-- I renamed include/sysemu/cpus.h => include/exec/vcpu.h
-- And other changes. Examples:
1) cpu_exec_init_all() in exec.c is about memory, and its name is kind 
of confusing
2) include/exec/address-spaces.h says below, but "git grep -nw 
address-spaces.h" reveals a lot.
/*
  * Internal interfaces between memory.c/exec.c/vl.c.  Do not #include 
unless
  * you're one of them.
  */

I am wondering if we should slightly re-factor the organization of 
files, thus new engineers will be easier to understand the design about 
tcg/exec.


2) Theoretically, include/exec/exec-all.h should work when included from 
*ANY files*, even mistakenly, right?

I hope this patch does NOT do any harm.

In my local repository, I split TranslationBlock related from it to be 
another file include/translate.h.

I will see what is the best way to "git send-email" these refactoring 
for the community to review, without causing too much confusion. The 
purpose is to make the design easier to understand for new engineers.


Thanks again.


On 02/26/2014 06:34 PM, Paolo Bonzini wrote:
> Il 26/02/2014 10:55, Peter Maydell ha scritto:
>> On 26 February 2014 09:25, Xuebing Wang <xbing6@gmail.com> wrote:
>>> This patch does below:
>>> -   Move the declaration of 2 translate functions from 
>>> translate-all.h into
>>>     include/exec/exec-all.h
>>> -   remove file translate-all.h
>>>
>>> "translate-all.h" => "exec/exec-all.h" can be done by:
>>> git grep -w "translate-all.h" | cut -d: -f1 |
>>>     xargs sed -i 's/\<translate-all.h\>/exec\/exec-all.h/g'
>>>
>>> Note:
>>> 1)  "exact whole word match" is considered.
>>> 2)  We may move translate related from include/exec/exec-all.h into
>>>     include/exec/translate.h later.
>>
>> Is there any particular benefit to this change? The function
>> prototypes go from being in a header only included by the file
>> that uses them to being in a header that's included by a lot
>> of other code...
>
> Indeed, that's the point of translate-all.h.
>
> Paolo
>
>

-- 
Thanks,
Xuebing Wang