[U-Boot-Users] [PATCH v2] net: Conditional COBJS inclusion of network drivers

[Ben Warren]

Hi Wolfgang,

welcome back...

Wolfgang Denk wrote:
> In message <484D4038.5000707 at ruby.dti.ne.jp> you wrote:
>   
>> Replace COBJS-y with appropriate driver config names.
>>
>> Signed-off-by: Shinya Kuribayashi <skuribay at ruby.dti.ne.jp>
>> ---
>>
>> Changes v2:
>>
>>  * Kill more CONFIG_CMD_NET and CONFIG_NET_MULTI defines from
>>    - fsl_mcdmafec.c
>>    - mcffec.c
>>    - netarm_eth.c
>>
>>  * Revised DM9000 part against the net repo.
>>     
>
> Hm... Are you absolutely sure your changes, especially the
> CONFIG_CMD_NET and even more the CONFIG_NET_MULTI related ones, do not
> cause any trouble on any systems?
>
> Let's for example check the E1000 network driver. with your changes,
> it will be built (and enabled), if...
>
> ...
>   
>> +COBJS-$(CONFIG_E1000) += e1000.o
>>     
> ...
>
> ... if CONFIG_E1000 is set.
>
> However, the old code:
>
> ...
>   
>> -#if defined(CONFIG_CMD_NET) \
>> -	&& defined(CONFIG_NET_MULTI) && defined(CONFIG_E1000)
>> -
>>     
>
> ...*also* required that CONFIG_CMD_NET *AND* CONFIG_NET_MULTI were
> set, too. 
>
> [For the E1000 driver this is easy to  verify,  as  only  few  boards
> enable this option, but you are changing this for many drivers, so it
> affects many boards...]
>
>
> It seems not obvious to me that your change is  really  harmless,  or
> tested.
>
> Could you please comment?
>
> [Note that I like your patch and would like to apply it (or  ask  Ben
> to do that), but it seems kind of risly to me...]
>
>   
I decided to accept this and push it upstream because it's definitely a 
step in the right direction.  Addressing your concerns, for any driver:

if CONFIG_CMD_NET isn't defined, networking isn't enabled, and at worst 
your image is bigger than necessary because of libnet.a

if CONFIG_NET_MULTI isn't defined, but CONFIG_CMD_NET is, networking 
will use the 'old-school' API and if the driver doesn't export 
eth_init() etc., you'll get a compile error.

So, IMHO the worst case scenario is a bit of code bloat or compile 
error, which aren't disastrous.  Run-time errors bad, compile-time, not 
so much.

Personally, I want to merge the two networking APIs so this MULTI 
business goes away.  Baby steps are necessary here.
> Best regards,
>
> Wolfgang Denk
>
>   
regards,
Ben