When I was running linux kernel on sifive unmatched board, I found that get_cycles() always return 0, this function will return the value of CSR_TIME register， It shouldn‘t be zero. but the CSR_CYCLE can be read and working properly.
By reading the SiFive FU740-C000 Manual. I realized that RTC may need a battery, and the problem persisted even after the battery was installed.
Then I add those code in Opensbi：
jj_mtime_addr = 0x0200_BFF8 （mtime register addr in clint）
And error occurs：
I don‘t known why CSR_TIME can't be access.
please help me
When I was running linux kernel on sifive unmatched board, I found that get_cycles() always return 0, this function will return the value of CSR_TIME register， It shouldn‘t be zero. but the CSR_CYCLE can be read and working properly. By reading the SiFive FU740-C000 Manual. I realized that RTC may need a battery, and the problem persisted even after the battery was installed. Then I add those code in Opensbi： jj_mtime_addr = 0x0200_BFF8 （mtime register addr in clint）
And error occurs：
I don‘t known why CSR_TIME can't be access. please help me