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Re: [PATCH] move __read_mostly to xen/cache.h


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Tue, 8 Aug 2023 12:32:51 +0200
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  • Cc: George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>, Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Tue, 08 Aug 2023 10:33:02 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 08.08.2023 12:18, Andrew Cooper wrote:
> On 08/08/2023 10:46 am, Jan Beulich wrote:
>> There's no need for every arch to define its own identical copy. If down
>> the road an arch needs to customize it, we can add #ifndef around the
>> common #define.
>>
>> To be on the safe side build-breakage-wise, change a couple of #include
>> <asm/cache.h> to the xen/ equivalent.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Could we find a better place to put this?
> 
> __read_mostly is just a section.  It's relationship to the cache is only
> microarchitectural, and is not the same kind of information as the rest
> of cache.h
> 
> __ro_after_init is only here because __read_mostly is here, but has
> absolutely nothing to do with caches whatsoever.
> 
> If we're cleaning them up, they ought to live elsewhere.

I would be considering init.h (for having most other __section() uses,
and for also needing __read_mostly), but that's not a great place to
put these either. In fact I see less connection there than for cache.h.
So the primary need is a good suggestion (I'm hesitant to suggest to
introduce section.h just for this). In the absence of this, can we
perhaps deal with this in a 2nd step, thus not blocking this patch and
therefore not needing to then also clean up PPC-specific code?

Jan



 


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