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  1. MariaDB Server
  2. MDEV-33435

RISC-V RDCYCLE cannot be accessed from userland

Details

    Description

      Starting with Linux kernel 6.6, the RDCYCLE instruction for RISC-V cannot be used with userland:

      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cc4c07c89aada16229084eeb93895c95b7eabaa3

      We use this in `my_rdtsc.h` for RISC-V platforms, which means this code does not work any more.

      Instead we should use RDTIME, which while less accurate has the advantage of being synchronized between CPU (and thus monotonic) and of constant frequency. This exists in earlier kernel versions too, so will not break backwards compatibility.

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          is caused by

          Task - A task that needs to be done. MDEV-27429 add clock timer support for RISC-V

          • Major - Major loss of function.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-34815 SIGILL error when executing mariadbd compiled for RISC-V with Clang

          • Major - Major loss of function.
          • Closed

          Activity

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            TheLinuxJedi Andrew Hutchings (Inactive) added a comment -

            Earliest affected release is 10.8, 10.11 is the first release that isn't EoL.

            TheLinuxJedi Andrew Hutchings (Inactive) added a comment - Earliest affected release is 10.8, 10.11 is the first release that isn't EoL.
            danblack Daniel Black added a comment - - edited

            Thanks Aurelien Jarno for the fix (656f8867720efc1b4dd0969319f35a3e1a2a005e).

            danblack Daniel Black added a comment - - edited Thanks Aurelien Jarno for the fix (656f8867720efc1b4dd0969319f35a3e1a2a005e).

            People

              TheLinuxJedi Andrew Hutchings (Inactive)
              TheLinuxJedi Andrew Hutchings (Inactive)
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              Dates

                Created:
                Updated:
                Resolved:

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