* [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 2:20 ` zhukeqian 0 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 2:20 UTC (permalink / raw) To: linux-arm-kernel, kvmarm@lists.cs.columbia.edu, Marc Zyngier, James Morse, Catalin Marinas, Will Deacon, Suzuki K, Poulose Cc: yebiaoxiang Hi all, We are studying Enhanced Counter Virtualization (introduced by ARMv8.6 extension), and here is a question raised by Biaoxiang Ye <yebiaoxiang@huawei.com>: 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? Thanks, Keqian _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm ^ permalink raw reply [flat|nested] 10+ messages in thread
* [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 2:20 ` zhukeqian 0 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 2:20 UTC (permalink / raw) To: linux-arm-kernel, kvmarm@lists.cs.columbia.edu, Marc Zyngier, James Morse, Catalin Marinas, Will Deacon, Suzuki K, Poulose Cc: yebiaoxiang, wanghaibin.wang, xiexiangyou Hi all, We are studying Enhanced Counter Virtualization (introduced by ARMv8.6 extension), and here is a question raised by Biaoxiang Ye <yebiaoxiang@huawei.com>: 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? Thanks, Keqian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization 2020-07-14 2:20 ` zhukeqian @ 2020-07-14 11:34 ` Marc Zyngier -1 siblings, 0 replies; 10+ messages in thread From: Marc Zyngier @ 2020-07-14 11:34 UTC (permalink / raw) To: zhukeqian Cc: Catalin Marinas, yebiaoxiang, Will Deacon, kvmarm, linux-arm-kernel 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@huawei.com>: > > 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... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 11:34 ` Marc Zyngier 0 siblings, 0 replies; 10+ messages in thread From: Marc Zyngier @ 2020-07-14 11:34 UTC (permalink / raw) To: zhukeqian Cc: Suzuki K, Poulose, Catalin Marinas, xiexiangyou, yebiaoxiang, James Morse, wanghaibin.wang, Will Deacon, kvmarm, linux-arm-kernel 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@huawei.com>: > > 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... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization 2020-07-14 11:34 ` Marc Zyngier @ 2020-07-14 12:15 ` zhukeqian -1 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 12:15 UTC (permalink / raw) To: Marc Zyngier Cc: Catalin Marinas, yebiaoxiang, Will Deacon, kvmarm, linux-arm-kernel Hi Marc, On 2020/7/14 19:34, Marc Zyngier wrote: > 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@huawei.com>: >> >> 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). > Well, it's alpha release version :( . Many thanks! Thanks, Keqian > In any case, this is most probably a question for ARM's support > team, and not the kernel mailing lists. > > Thanks, > > M. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 12:15 ` zhukeqian 0 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 12:15 UTC (permalink / raw) To: Marc Zyngier Cc: Suzuki K, Poulose, Catalin Marinas, xiexiangyou, yebiaoxiang, James Morse, wanghaibin.wang, Will Deacon, kvmarm, linux-arm-kernel Hi Marc, On 2020/7/14 19:34, Marc Zyngier wrote: > 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@huawei.com>: >> >> 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). > Well, it's alpha release version :( . Many thanks! Thanks, Keqian > In any case, this is most probably a question for ARM's support > team, and not the kernel mailing lists. > > Thanks, > > M. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization 2020-07-14 12:15 ` zhukeqian @ 2020-07-14 12:23 ` Marc Zyngier -1 siblings, 0 replies; 10+ messages in thread From: Marc Zyngier @ 2020-07-14 12:23 UTC (permalink / raw) To: zhukeqian Cc: Catalin Marinas, yebiaoxiang, Will Deacon, kvmarm, linux-arm-kernel On 2020-07-14 13:15, zhukeqian wrote: > Hi Marc, > > On 2020/7/14 19:34, Marc Zyngier wrote: >> 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@huawei.com>: >>> >>> 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). >> > Well, it's alpha release version :( . Many thanks! Wow. I suggest you discard this document, as it is obsolete. ARMv8.6 is a released version of the architecture, and everything should be in the ARM ARM. M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 12:23 ` Marc Zyngier 0 siblings, 0 replies; 10+ messages in thread From: Marc Zyngier @ 2020-07-14 12:23 UTC (permalink / raw) To: zhukeqian Cc: Suzuki K, Poulose, Catalin Marinas, xiexiangyou, yebiaoxiang, James Morse, wanghaibin.wang, Will Deacon, kvmarm, linux-arm-kernel On 2020-07-14 13:15, zhukeqian wrote: > Hi Marc, > > On 2020/7/14 19:34, Marc Zyngier wrote: >> 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@huawei.com>: >>> >>> 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). >> > Well, it's alpha release version :( . Many thanks! Wow. I suggest you discard this document, as it is obsolete. ARMv8.6 is a released version of the architecture, and everything should be in the ARM ARM. M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization 2020-07-14 12:23 ` Marc Zyngier @ 2020-07-14 13:22 ` zhukeqian -1 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 13:22 UTC (permalink / raw) To: Marc Zyngier Cc: Catalin Marinas, yebiaoxiang, Will Deacon, kvmarm, linux-arm-kernel On 2020/7/14 20:23, Marc Zyngier wrote: > On 2020-07-14 13:15, zhukeqian wrote: >> Hi Marc, >> >> On 2020/7/14 19:34, Marc Zyngier wrote: >>> 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@huawei.com>: >>>> >>>> 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). >>> >> Well, it's alpha release version :( . Many thanks! > > Wow. I suggest you discard this document, as it is obsolete. > ARMv8.6 is a released version of the architecture, and > everything should be in the ARM ARM. OK, there are many difference :) . Thanks, Keqian > > M. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Question] About scaling factor of Enhanced Counter Virtualization @ 2020-07-14 13:22 ` zhukeqian 0 siblings, 0 replies; 10+ messages in thread From: zhukeqian @ 2020-07-14 13:22 UTC (permalink / raw) To: Marc Zyngier Cc: Suzuki K, Poulose, Catalin Marinas, xiexiangyou, yebiaoxiang, James Morse, wanghaibin.wang, Will Deacon, kvmarm, linux-arm-kernel On 2020/7/14 20:23, Marc Zyngier wrote: > On 2020-07-14 13:15, zhukeqian wrote: >> Hi Marc, >> >> On 2020/7/14 19:34, Marc Zyngier wrote: >>> 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@huawei.com>: >>>> >>>> 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). >>> >> Well, it's alpha release version :( . Many thanks! > > Wow. I suggest you discard this document, as it is obsolete. > ARMv8.6 is a released version of the architecture, and > everything should be in the ARM ARM. OK, there are many difference :) . Thanks, Keqian > > M. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2020-07-14 13:24 UTC | newest] Thread overview: 10+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-07-14 2:20 [Question] About scaling factor of Enhanced Counter Virtualization zhukeqian 2020-07-14 2:20 ` zhukeqian 2020-07-14 11:34 ` Marc Zyngier 2020-07-14 11:34 ` Marc Zyngier 2020-07-14 12:15 ` zhukeqian 2020-07-14 12:15 ` zhukeqian 2020-07-14 12:23 ` Marc Zyngier 2020-07-14 12:23 ` Marc Zyngier 2020-07-14 13:22 ` zhukeqian 2020-07-14 13:22 ` zhukeqian
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