On 30/01/2019 16:31, Juergen Gross wrote:
> On 30/01/2019 16:55, Andrew Cooper wrote:
>> Xen will warn when an unknown parameter is found in the command line.  e.g.
>>
>>   (d8) [ 1556.334664] (XEN) parameter "pv-shim" unknown!
>>
>> One case where this goes wrong is a workaround for an old grub bug, which
>> resulted in "placeholder" being prepended to the command line.
>>
>> Another case is when booting a CONFIG_PV_SHIM_EXCLUSIVE build, in which the
>> parsing for the "pv-shim" parameter is discarded.
>>
>> Introduce ignore_param() and OPT_IGNORE to cope with known cases, where
>> warning the user is the wrong course of action to take.
>>
>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
>> ---
>> CC: Jan Beulich <jbeul...@suse.com>
>> CC: Wei Liu <wei.l...@citrix.com>
>> CC: Roger Pau Monné <roger....@citrix.com>
>> CC: Juergen Gross <jgr...@suse.com>
>>
>> v2:
>>  * Rewrite from scratch, following Juergen's suggestion
>>
>> An implementation detail of ignore_param() is that it can only be used once
>> per translation unit, which is fine for now.  Two options to fix this are to
>> tokenise __LINE__ in (requires some extreme preprocessor magic to make work,
>> as ## inhibits expansion, and may cause livepatching issues), or to retain 
>> the
>> _val parameter and require callers to just pass in a unique string.
> Or make the unique string an optional parameter via:
>
> #define ignore_param(_name, uniq...)                \
>     __setup_str __setup_str_ign ## uniq[] = _name;  \
>     __kparam __setup_ign ## uniq =                  \
>         { .name = __setup_str_ign ## uniq,          \
>           .type = OPT_IGNORE }
>
> With or without that change:
>
> Reviewed-by: Juergen Gross <jgr...@suse.com>
> Release-acked-by: Juergen Gross <jgr...@suse.com>

Actually I like this as an option.  I'll fold this in, along with Jan's
namespacing request.

~Andrew

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