https://community.intel.com/t5/Intel-ISA-Extensions/Obtain-time-stamp-disable-TSD-flag-in-user-mode/m-p/773690#M156 I need to check if the rdtsc instruction is supported by the processor and the operating system. The processor part is easy been done, but I have problem to check if the operation system is supporting this in other privileges than 0.<BR /><BR />The general way is to read bit 2 from the control register CR4, but I cannot do this in PL3. Is there any workaround? I don't want to cause a Privileged Instruction exception. Tue, 29 Mar 2011 12:54:39 GMT freeze2046 2011-03-29T12:54:39Z https://community.intel.com/t5/Intel-ISA-Extensions/Obtain-time-stamp-disable-TSD-flag-in-user-mode/m-p/773690#M156 I need to check if the rdtsc instruction is supported by the processor and the operating system. The processor part is easy been done, but I have problem to check if the operation system is supporting this in other privileges than 0.<BR /><BR />The general way is to read bit 2 from the control register CR4, but I cannot do this in PL3. Is there any workaround? I don't want to cause a Privileged Instruction exception. Tue, 29 Mar 2011 12:54:39 GMT https://community.intel.com/t5/Intel-ISA-Extensions/Obtain-time-stamp-disable-TSD-flag-in-user-mode/m-p/773690#M156 freeze2046 2011-03-29T12:54:39Z https://community.intel.com/t5/Intel-ISA-Extensions/Obtain-time-stamp-disable-TSD-flag-in-user-mode/m-p/773691#M157 If you are on Linux, you can use something like the following:<BR /><BR />#include <STDBOOL.H><BR />#include <LINUX><BR /><BR />bool<BR />is_rdtsc_supported(void)<BR />{<BR /> int tsc_supported = PR_TSC_SIGSEGV;<BR /><BR /> if (prctl(PR_GET_TSC, &amp;tsc_supported) &lt; 0)<BR /> return false;<BR /><BR /> return tsc_supported == PR_TSC_ENABLE;<BR />}<BR /></LINUX></STDBOOL.H> Sat, 21 May 2011 06:16:16 GMT https://community.intel.com/t5/Intel-ISA-Extensions/Obtain-time-stamp-disable-TSD-flag-in-user-mode/m-p/773691#M157 Chris_Hooper 2011-05-21T06:16:16Z