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Re: [Xen-devel] [PATCH v2 4/5] xen/gnttab: Refactor gnttab_clear_flag() to be gnttab_clear_flags()



Hi,

On 7/8/19 7:11 PM, Andrew Cooper wrote:
On 07/07/2019 19:42, Julien Grall wrote:
Hi Andrew,

On 7/4/19 8:14 PM, Andrew Cooper wrote:
To allow for further improvements, it is useful to be able to clear
more than
a single flag at once.  Rework gnttab_clear_flag() into
gnttab_clear_flags()
which takes a bitmask rather than a bit number.

No practical change yet.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

v2:
   * Use unsigned int for the mask parameter

I don't seem to find the request on the ML. Technically the mask can
only be 16-bit. May I ask the reason of this change?

It is on the mailing list, but an orphaned email due to Jan's email changes.

Is it the same problem as I have seen the past 6 months between Juergen and Jan's e-mail?


https://lore.kernel.org/xen-devel/1561109798-8744-5-git-send-email-andrew.cooper3@xxxxxxxxxx/T/#t

To be honest, I think it is wrong to try to micro-optimize a common prototype for the benefit of one architecture and one compiler version (or even none per the e-mail).

One could also argue that this may be not beneficial for the non-x86 architecture depending on how the compiler decide to do the cast from 32-bit to 16-bit...

Cheers,

--
Julien Grall

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