Hi Keqian,
On 2020-07-14 03:20, zhukeqian wrote:
Hi all,
We are studying Enhanced Counter Virtualization (introduced by ARMv8.6
extension), and here is a question
raised by Biaoxiang Ye <yebiaoxiang@xxxxxxxxxx>:
Described in the ARMv8.6 Extension Specification:
Note: the scaling factor CNTSCALE is designed as a 2.62 bit fixed
point number, so permitting a scaling up by
(nearly) a factor 4. The scaling factor CNTISCALE is signed as an 8.56
number for the scaling of the values
written into the timers for comparison with the actual count. This
implies that the greatest scaling down of the
counter supported in (nearly) a factor of *512*.
We think the number "512" should be "256" (2^8), or do we miss
something?
This register doesn't seem to be described in ARM DDI 0487F.b,
which is the official documentation and does contain the ARMv8.6
material, including ARMv8.6-ECV.
Either you are looking at confidential information (and nobody
can answer you in public), or obsolete information (and nobody
knows what this is about).
In any case, this is most probably a question for ARM's support
team, and not the kernel mailing lists.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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