Re: [PATCH kvmtool] Makefile: 'lvm version' works incorrect. Because CFLAGS can not get sub-make variable $(KVMTOOLS_VERSION)

From: "haibiao.xiao" <haibiao.xiao@zstack.io>
To: Andre Przywara <andre.przywara@arm.com>
Cc: kvm@vger.kernel.org, will@kernel.org,
	julien.thierry.kdev@gmail.com,
	"haibiao.xiao" <xiaohaibiao331@outlook.com>,
	Alexandru Elisei <Alexandru.Elisei@arm.com>
Subject: Re: [PATCH kvmtool] Makefile: 'lvm version' works incorrect. Because CFLAGS can not get sub-make variable $(KVMTOOLS_VERSION)
Date: Fri, 10 Dec 2021 10:55:40 +0800	[thread overview]
Message-ID: <28ff4bb3-851a-e287-b008-c2a91370c90d@zstack.io> (raw)
In-Reply-To: <20211209155746.3f6bd016@donnerap.cambridge.arm.com>

Hi,

On Thu, 9 Dec 2021 15:57:46 +0000, Andre Przywara wrote:
> On Sat,  4 Dec 2021 14:14:36 +0800
> "haibiao.xiao" <haibiao.xiao@zstack.io> wrote:
> 
> Hi,
> 
>> From: "haibiao.xiao" <xiaohaibiao331@outlook.com>
>>
>> Command 'lvm version' works incorrect.
>> It is expected to print:
>>
>>     # ./lvm version
>>     # kvm tool [KVMTOOLS_VERSION]
>>
>> but the KVMTOOLS_VERSION is missed:
>>
>>     # ./lvm version
>>     # kvm tool
>>
>> The KVMTOOLS_VERSION is defined in the KVMTOOLS-VERSION-FILE file which
>> is included at the end of Makefile. Since the CFLAGS is a 'Simply
>> expanded variables' which means CFLAGS is only scanned once. So the
>> definetion of KVMTOOLS_VERSION at the end of Makefile would not scanned
>> by CFLAGS. So the '-DKVMTOOLS_VERSION=' remains empty.
>>
>> I fixed the bug by moving the '-include $(OUTPUT)KVMTOOLS-VERSION-FILE'
>> before the CFLAGS.
> 
> While this is indeed a bug that this patch fixes, I wonder if we should
> actually get rid of this whole versioning attempt altogether at this
> point. Originally this was following the containing kernel version, but
> it is stuck ever since at v3.18, without any change.
> 
> So either we introduce proper versioning (not sure it's worth it?), or we
> just remove all code that pretends to print a version number? Or just
> hardcode v3.18 into the printf, at least for now? At the very least I
> think we don't need a KVMTOOLS-VERSION-FILE anymore.
> 

Thanks for your reply. 

The reason I look at this project is tend to learn something about kvm. 
With the version number I can tell which kernel(kvm) is compatible.

Although it is stuck at v3.18, there still some commits in recent 
months, which means the kvmtool still changing according to the kvm 
features. So I think what's kvmtool need is a version control, but not 
remove/hardcode.

Thanks,
haibiao.xiao
> Cheers,
> Andre
> 
>>
>> Signed-off-by: haibiao.xiao <xiaohaibiao331@outlook.com>
>> ---
>>  Makefile | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index bb7ad3e..9afb5e3 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -17,6 +17,7 @@ export E Q
>>  
>>  include config/utilities.mak
>>  include config/feature-tests.mak
>> +-include $(OUTPUT)KVMTOOLS-VERSION-FILE
>>  
>>  CC	:= $(CROSS_COMPILE)gcc
>>  CFLAGS	:=
>> @@ -559,5 +560,4 @@ ifneq ($(MAKECMDGOALS),clean)
>>  
>>  KVMTOOLS-VERSION-FILE:
>>  	@$(SHELL_PATH) util/KVMTOOLS-VERSION-GEN $(OUTPUT)
>> --include $(OUTPUT)KVMTOOLS-VERSION-FILE
>> -endif
>> +endif
>> \ No newline at end of file