On Fri, Aug 08, 2008 at 02:27:42PM -0400, John Baldwin wrote: > On Friday 08 August 2008 02:10:52 pm Kostik Belousov wrote: > > On Fri, Aug 08, 2008 at 12:51:17PM -0400, John Baldwin wrote: > > > On Friday 08 August 2008 12:26:53 pm Stanislav Sedov wrote: > > > > stas 2008-08-08 16:26:53 UTC > > > > > > > > FreeBSD src repository > > > > > > > > Modified files: > > > > share/man/man4 Makefile > > > > sys/amd64/amd64 support.S > > > > sys/amd64/conf NOTES > > > > sys/amd64/include cpufunc.h specialreg.h > > > > sys/conf files.amd64 files.i386 > > > > sys/i386/conf NOTES > > > > sys/i386/i386 support.s > > > > sys/i386/include cpufunc.h specialreg.h > > > > sys/modules Makefile > > > > sys/sys priv.h > > > > usr.sbin Makefile > > > > Added files: > > > > share/man/man4 cpuctl.4 > > > > sys/dev/cpuctl cpuctl.c > > > > sys/modules/cpuctl Makefile > > > > sys/sys cpuctl.h > > > > usr.sbin/cpucontrol Makefile amd.c amd.h cpucontrol.8 > > > > cpucontrol.c cpucontrol.h intel.c intel.h > > > > Log: > > > > SVN rev 181430 on 2008-08-08 16:26:53Z by stas > > > > > > > > - Add cpuctl(4) pseudo-device driver to provide access to some > low-level > > > > features of CPUs like reading/writing machine-specific registers, > > > > retrieving cpuid data, and updating microcode. > > > > - Add cpucontrol(8) utility, that provides userland access to > > > > the features of cpuctl(4). > > > > - Add subsequent manpages. > > > > > > > > The cpuctl(4) device operates as follows. The pseudo-device node > cpuctlX > > > > is created for each cpu present in the systems. The pseudo-device > minor > > > > number corresponds to the cpu number in the system. The cpuctl(4) > pseudo- > > > > device allows a number of ioctl to be preformed, namely > RDMSR/WRMSR/CPUID > > > > and UPDATE. The first pair alows the caller to read/write > machine-specific > > > > registers from the correspondent CPU. cpuid data could be retrieved > using > > > > the CPUID call, and microcode updates are applied via UPDATE. > > > > > > > > The permissions are inforced based on the pseudo-device file > permissions. > > > > RDMSR/CPUID will be allowed when the caller has read access to the > device > > > > node, while WRMSR/UPDATE will be granted only when the node is opened > > > > for writing. There're also a number of priv(9) checks. > > > > > > > > The cpucontrol(8) utility is intened to provide userland access to > > > > the cpuctl(4) device features. The utility also allows one to apply > > > > cpu microcode updates. > > > > > > > > Currently only Intel and AMD cpus are supported and were tested. > > > > > > Note that cpuid isn't a privileged instruction, so I'm not sure it's > really > > > worth having an ioctl for that particular case. > > > > It was discussed when patch was reviewed on [EMAIL PROTECTED] The ioctl > > allows > > to get cpuid information for specific processor, as opposed to some > > random core curthread happens to run ATM. > > You can achieve that now with cpuset. :) (See my ping-pong test program > recently which used cpuid to fetch the APIC ID to test for ping-ponging in > the scheduler.)
If this is a backout request (for cpuid functionality) then we will do it.
But I considered it much easier and cleaner to do
fd = open("/dev/cpuctlN", O_RDWR);
ioctl(fd, CPUCTL_CPUID, &x);
if (x.y)
ioctl(fd, CPUCTL_WRMSR, ...);
close(fd);
then
fd = open("/dev/cpuctlN", O_RDWR);
cpuset(...); /* bind to cpu */
__asm__("cpuid" : =0 (x));
if (x.y)
ioctl(fd, CPUCTL_WRMSR, ...);
cpuset(...); /* restore prev mask */
close(fd);
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