Re: [dpdk-dev] [PATCH v2 1/2] mk: allow use of environment var for make config

[Shreyansh Jain <shreyansh.jain@nxp.com>]

On Wednesday 07 June 2017 03:58 PM, Hunt, David wrote:
> Hi Shreyansh,
> 
> 
> On 7/6/2017 10:36 AM, Shreyansh Jain wrote:
>> Hello David,
>>
>> On Wednesday 07 June 2017 02:09 PM, Hunt, David wrote:
>>> Shreyansh,
>>>
>>>      I found an issue (or two) with this part of the patch, and have 
>>> a proposed solution.
>>>
>>> 1. RTE_TARGET originally had a different meaning. It was used for 
>>> making examples, specifying the target directory of where the SDK was 
>>> built. It's not good to re-purpose this for something else, as I'm 
>>> doing in this patch. (even though I'm not sure that variable is 
>>> suitably named in the first place, but that's a different issue).
>>
>> Even I didn't realize this until you highlighted here.
>>
>>> 2. If we set RTE_TARGET on the environment, we will break the 'make 
>>> -C examples/<app>', unless we set RTE_TARGET to be something else 
>>> (i.e. 'make -C examples/<app> RTE_TARGET=build'). One value for 
>>> making DPDK, and another for building examples. It's confusing to the 
>>> user.
>>
>> Agree about re-using RTE_TARGET is breaking existing assumption about
>> its use.
>>
>>>
>>> An alternative patch would be as follows:
>>>
>>>   RTE_CONFIG_TEMPLATE :=
>>>   ifdef T
>>> *-ifeq ("$(origin T)", "command line")*
>>>   RTE_CONFIG_TEMPLATE := $(RTE_SRCDIR)/config/defconfig_$(T)
>>> *-endif**
>>> *endif
>>>   export RTE_CONFIG_TEMPLATE
>> So, that would mean, user would do either of the following:
>>
>> make T=<template> config
>>
>> or
>>
>> export T=<template>
>> make config
>>
>> Is that correct? (I tried it and it seems to be working fine)
>> First method is same as today. For the second, I am just skeptical
>> whether we should use such a small identifier ("T") or we have a new
>> RTE_TEMPLATE.
>>
>> Either way, I am OK. [export T=<template>] looks fine to me - in fact,
>> on a second though, IMO, if T=<template> is provided as command line, 
>> it should also be acceptable as env variable.
>>
> 
> I did a quick poll here in the office and people feel that 'T' is too 
> short for an environment variable. RTE_TEMPLATE would be preferred, and 
> it's a sensible choice that does not conflict with RTE_TARGET.
> 
> So if we use RTE_TEMPLATE, we'd also have to put in a couple of lines 
> for the "make install" case, but it's still a small enough patch:
> 
> diff --git a/mk/rte.sdkinstall.mk b/mk/rte.sdkinstall.mk
> index dbac2a2..a464b01 100644
> --- a/mk/rte.sdkinstall.mk
> +++ b/mk/rte.sdkinstall.mk
> @@ -47,6 +47,10 @@ ifneq ($(MAKECMDGOALS),pre_install)
>   include $(RTE_SDK)/mk/rte.vars.mk
>   endif
> 
> *+ifndef T**
> **+T := $(RTE_TEMPLATE)**
> **+endif**
> * ifdef T # defaults with T= will install an almost flat staging tree
>   export prefix ?=
>   kerneldir   ?= $(prefix)/kmod
> 
> 
> diff --git a/mk/rte.sdkroot.mk b/mk/rte.sdkroot.mk
> index 076a2d7..0b71a4e 100644
> --- a/mk/rte.sdkroot.mk
> +++ b/mk/rte.sdkroot.mk
> @@ -63,6 +63,8 @@ ifdef T
>   ifeq ("$(origin T)", "command line")
>   RTE_CONFIG_TEMPLATE := $(RTE_SRCDIR)/config/defconfig_$(T)
>   endif
> *+else**
> **+RTE_CONFIG_TEMPLATE := $(RTE_SRCDIR)/config/defconfig_$(RTE_TEMPLATE)**
> * endif
>   export RTE_CONFIG_TEMPLATE
> 
> So if T is provided on the command line, it takes priority.
> If that seems reasonable to you, I'll push up a v3. :)

Sounds good to me.
Feel free to add my signoff to v3.

> 
> Regards,
> Dave.
> 
> 
> 
> 
>