Re: [PATCH v6 2/3] clocksource/drivers/atcpit100: VDSO support

2018-01-20 Thread Vincent Chen
Correct the composition Dear Arnd: 1. Setup an additional memory mapping for clock hardware in user space when establishing vdso-needed memory mapping In arch_setup_additional_pages(), kernel establishes memory mapping for vdso's text and vdata page in user space. In order to make clock

Re: [PATCH v6 2/3] clocksource/drivers/atcpit100: VDSO support

2018-01-20 Thread Vincent Chen
2018-01-18 19:08 GMT+08:00 Arnd Bergmann : > On Mon, Jan 15, 2018 at 6:57 AM, Greentime Hu wrote: >> From: Rick Chen >> >> VDSO needs real-time cycle count to ensure the time accuracy. >> Unlike others, nds32 architecture does not define

Re: [PATCH v6 2/3] clocksource/drivers/atcpit100: VDSO support

2018-01-18 Thread Arnd Bergmann
On Mon, Jan 15, 2018 at 6:57 AM, Greentime Hu wrote: > From: Rick Chen > > VDSO needs real-time cycle count to ensure the time accuracy. > Unlike others, nds32 architecture does not define clock source, > hence VDSO needs atcpit100 offering real-time

[PATCH v6 2/3] clocksource/drivers/atcpit100: VDSO support

2018-01-14 Thread Greentime Hu
From: Rick Chen VDSO needs real-time cycle count to ensure the time accuracy. Unlike others, nds32 architecture does not define clock source, hence VDSO needs atcpit100 offering real-time cycle count to derive the correct time. Signed-off-by: Vincent Chen