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Re: [PATCH 4/5] xen: Split muldiv64() out of lib.h
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: "Orzel, Michal" <michal.orzel@xxxxxxx>
- Date: Wed, 7 Jan 2026 10:28:43 +0100
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- Cc: Jan Beulich <JBeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, "Julien Grall" <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
- Delivery-date: Wed, 07 Jan 2026 09:28:55 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 30/12/2025 14:50, Andrew Cooper wrote:
> muldiv64() has 7 users across all architectures, and is limited to time
> handling functions. Therefore, move it's declaration out of lib.h into a
> dedicated header.
>
> Rename the library function to generic_muldiv64(), as x86 is going to provide
> an arch_muldiv64() in a subsequent change.
>
> Explain what the function does, including the limitations; x86's version will
> suffer a divide error rather than truncate the result to 64 bits.
>
> Annotate it with attr_const, not that this allows the optimiser to improve any
> of Xen's current users. Add one selftest to check the internal precision,
> putting it in bitops.c for want of any better place to locate it.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
For Arm:
Acked-by: Michal Orzel <michal.orzel@xxxxxxx>
~Michal
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