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Re: [Xen-devel] [PATCH v4 2/3] bitmap: import bitmap_{set/clear} from Linux 5.5

On 10/02/2020 12:32, Jan Beulich wrote:
On 10.02.2020 13:21, Julien Grall wrote:

On 10/02/2020 11:59, Jan Beulich wrote:
On 10.02.2020 12:00, Julien Grall wrote:
On 10/02/2020 10:28, Jan Beulich wrote:
On 10.02.2020 10:45, Julien Grall wrote:
Please suggest a new name for BIT_WORD() and we can repurpose it. So
far, I have no idea how to rename it.

_BIT_WORD() if you/we were to accept the name space violation, or

BITMAP_WORD() is misleading as bitmap are using unsigned long. So my
preference is _BIT_WORD().

Another alternative would be ATOMIC_WORD().

Except that there are also non-atomic bitmap operations, I don't really
care about the name as long as it's not BIT_WORD() (or anything else
that's likely to collide with other stuff.

I am afraid we are disagreing on what is colliding with what here. The
naming on Arm has been like that for the past few years. While this may
not have been the best choice, this is your suggestion colliding with
what is existing.

It is a plain import from Linux which has turned out impossible
because of the change that was done at some point to Arm code
which, I guess, also originally came from Linux. There's no new
naming I've been suggesting here at all.

We never claimed we would be fully compatible with Linux and I don't think we could every claim it. Particularly, the bitop operations are different given Linux bitops are based on unsigned long.

The bitop did indeed came from Linux originally, however we had to adapt them because Linux Armv8 bitop was expecting 8-byte aligned. This does not hold on Xen.

I am not entirely fussed about the namespace violation, although I think
the name is potentially misleading. Yet, I would be happy to use
_BIT_WORD() as this is the best of it so far.

While this is code falls under Arm maintainership, I am still happy to
consider other naming. But at this point, you should be the one suggesting.




Julien Grall

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