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Re: [PATCH v2 06/16] xen/time: move ticks<->ns helpers to common code
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
- Date: Wed, 4 Feb 2026 10:00:12 +0100
- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Alistair Francis <alistair.francis@xxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, Romain Caritey <Romain.Caritey@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Wed, 04 Feb 2026 09:00:24 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 2/4/26 9:13 AM, Jan Beulich wrote:
On 29.01.2026 09:48, Jan Beulich wrote:
On 22.01.2026 17:47, Oleksii Kurochko wrote:
ticks_to_ns() and ns_to_ticks() are not architecture-specific, so provide a
common implementation that is more resilient to overflow than the historical
Arm version. This is not a practical issue for Arm, as the latest ARM ARM
that timer frequency should be fixed at 1 GHz and older platforms used much
lower rates, which is shy of 32-bit overflow. As the helpers are declared
as static inline, they should not affect x86, which does not use them.
On Arm, these helpers were historically implemented as out-of-line functions
because the counter frequency was originally defined as static and unavailable
to headers [1]. Later changes [2] removed this restriction, but the helpers
remained unchanged. Now they can be implemented as static inline without any
issues.
Centralising the helpers avoids duplication and removes subtle differences
between architectures while keeping the implementation simple.
Drop redundant <asm/time.h> includes where <xen/time.h> already pulls it in.
No functional change is intended.
[1] ddee56dc2994 arm: driver for the generic timer for ARMv7
[2] 096578b4e489 xen: move XEN_SYSCTL_physinfo, XEN_SYSCTL_numainfo and
XEN_SYSCTL_topologyinfo to common code
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
Nit: Flip the two (chronological order).
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Btw, if this got the necessary Arm ack, I think it could also go in ahead of
all earlier patches in the series?
Yes, it is independent from earlier patches in the series.
~ Oleksii
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