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Date:      Fri, 8 Aug 2008 12:51:17 -0400
From:      John Baldwin <jhb@freebsd.org>
To:        Stanislav Sedov <stas@freebsd.org>
Cc:        cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org
Subject:   Re: cvs commit: src/share/man/man4 Makefile cpuctl.4 src/sys/amd64/amd64 support.S src/sys/amd64/conf NOTES src/sys/amd64/include cpufunc.h specialreg.h src/sys/conf files.amd64 files.i386 src/sys/dev/cpuctl cpuctl.c ...
Message-ID:  <200808081251.17686.jhb@freebsd.org>
In-Reply-To: <200808081631.m78GVG9i088754@repoman.freebsd.org>
References:  <200808081631.m78GVG9i088754@repoman.freebsd.org>

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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.

-- 
John Baldwin



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