Re: [Xen-devel] [RFC PATCH V2 1/8] xen/mem_event: Cleanup of mem_event structures

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Thu, Jan 29, 2015 at 1:02 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 29.01.15 at 12:54, <tamas.lengyel@xxxxxxxxxxxx> wrote:
>> On Thu, Jan 22, 2015 at 4:34 PM, Tamas K Lengyel
>> <tamas.lengyel@xxxxxxxxxxxx> wrote:
>>> On Thu, Jan 22, 2015 at 4:00 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>>> On 18.01.15 at 16:17, <tamas.lengyel@xxxxxxxxxxxx> wrote:
>>>>> --- a/xen/include/Makefile
>>>>> +++ b/xen/include/Makefile
>>>>> @@ -90,7 +90,7 @@ ifeq ($(XEN_TARGET_ARCH),$(XEN_COMPILE_ARCH))
>>>>>
>>>>>  all: headers.chk
>>>>>
>>>>> -headers.chk: $(filter-out public/arch-% public/%ctl.h public/xsm/%
>>>>> public/%hvm/save.h, $(wildcard public/*.h public/*/*.h) $(public-y)) 
>>>>> Makefile
>>>>> +headers.chk: $(filter-out public/arch-% public/%ctl.h public/mem_event.h
>>>>> public/xsm/% public/%hvm/save.h, $(wildcard public/*.h public/*/*.h)
>>>>> $(public-y)) Makefile
>>>>
>>>> I think you should finally break this already too long line. But of course
>>>> first of all you'll want to explain why the addition is necessary/correct.
>>>> The mere fact that this now becomes a tools-only interface isn't
>>>> enough imo - some of the other headers excluded here would better
>>>> undergo the checking too, just that first they would need cleaning up.
>>>
>>> I have to revisit what is actually going on here, I believe I had to
>>> add this to get Xen to build. On a second look not sure why that was.
>>
>> So I double checked and the addition here is correct, without
>> excluding the header, the compilation fails at #if !defined(__XEN__)
>> && !defined(__XEN_TOOLS__) in mem_event.h.
>
> Hardly at that line. I'm afraid I won't be convinced without you
> explaining what fails why, and why that can't be dealt with.
>
>> So I'll break the line but
>> cleaning up/checking the other headers IMHO is out of scope for this
>> series.
>
> Of course, no-one asked you to do this (and even less so in this series).
>
> Jan

The reason why compilation fails is because the new preprocessor check
in mem_event.j #if !defined(__XEN__) && !defined(__XEN_TOOLS__) is not
happy and I get the error message #error "vm event operations are
intended for use only by Xen or node control tools". This is a new
addition into the mem_event.h thus the build without this
pre-processor check works just fine. All other headers within
include/public that have similar preprocessor checks are already
excluded in this line, thus my impression was this is the correct way
to get the build to progress. Of course if I missed something please
let me know, I don't honestly fully comprehend the build process here.

Thanks,
Tamas

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