Re: [PATCH] [net] nvmem: disallow modular CONFIG_NVMEM

[David Miller <davem@davemloft.net>]

From: Arnd Bergmann <arnd@arndb.de>
Date: Wed,  4 Apr 2018 12:38:40 +0200

> The new of_get_nvmem_mac_address() helper function causes a link error
> with CONFIG_NVMEM=m:
> 
> drivers/of/of_net.o: In function `of_get_nvmem_mac_address':
> of_net.c:(.text+0x168): undefined reference to `of_nvmem_cell_get'
> of_net.c:(.text+0x19c): undefined reference to `nvmem_cell_read'
> of_net.c:(.text+0x1a8): undefined reference to `nvmem_cell_put'
> 
> I could not come up with a good solution for this, as the code is always
> built-in. Using an #if IS_REACHABLE() check around it would solve the
> link time issue but then stop it from working in that configuration.
> Making of_nvmem_cell_get() an inline function could also solve that, but
> seems a bit ugly since it's somewhat larger than most inline functions,
> and it would just bring that problem into the callers.  Splitting the
> function into a separate file might be an alternative.
> 
> This uses the big hammer by making CONFIG_NVMEM itself a 'bool' symbol,
> which avoids the problem entirely but makes the vmlinux larger for anyone
> that might use NVMEM support but doesn't need it built-in otherwise.
> 
> Fixes: 9217e566bdee ("of_net: Implement of_get_nvmem_mac_address helper")
> Cc: Mike Looijmans <mike.looijmans@topic.nl>
> Cc: Florian Fainelli <f.fainelli@gmail.com>
> Cc: Andrew Lunn <andrew@lunn.ch>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> The problem arrived through the networking tree, but it's now in
> mainline, so the fix could go through either tree

Ok, applied, thanks Arnd.