| 1 | .\" Copyright (c) 2008 Yahoo!, Inc. |
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| 2 | .\" All rights reserved. |
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| 3 | .\" Written by: John Baldwin <jhb@FreeBSD.org> |
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| 4 | .\" |
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| 5 | .\" Redistribution and use in source and binary forms, with or without |
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| 6 | .\" modification, are permitted provided that the following conditions |
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| 8 | .\" 1. Redistributions of source code must retain the above copyright |
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| 9 | .\" notice, this list of conditions and the following disclaimer. |
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| 11 | .\" notice, this list of conditions and the following disclaimer in the |
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| 13 | .\" 3. Neither the name of the author nor the names of any co-contributors |
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| 17 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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| 29 | .\" $FreeBSD$ |
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| 30 | .\" |
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| 31 | .Dd August 19, 2008 |
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| 32 | .Dt KVM_GETPCPU 3 |
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| 33 | .Os |
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| 34 | .Sh NAME |
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| 35 | .Nm kvm_getmaxcpu , |
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| 36 | .Nm kvm_getpcpu |
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| 37 | .Nd access per-CPU data |
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| 38 | .Sh LIBRARY |
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| 39 | .Lb libkvm |
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| 40 | .Sh SYNOPSIS |
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| 41 | .In sys/param.h |
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| 42 | .In sys/pcpu.h |
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| 43 | .In sys/sysctl.h |
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| 44 | .In kvm.h |
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| 45 | .Ft int |
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| 46 | .Fn kvm_getmaxcpu "kvm_t *kd" |
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| 47 | .Ft void * |
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| 48 | .Fn kvm_getpcpu "kvm_t *kd" "int cpu" |
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| 49 | .Sh DESCRIPTION |
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| 50 | The |
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| 51 | .Fn kvm_getmaxcpu |
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| 52 | and |
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| 53 | .Fn kvm_getpcpu |
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| 54 | functions are used to access the per-CPU data of active processors in the |
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| 55 | kernel indicated by |
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| 56 | .Fa kd . |
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| 57 | The |
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| 58 | .Fn kvm_getmaxcpu |
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| 59 | function returns the maximum number of CPUs supported by the kernel. |
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| 60 | The |
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| 61 | .Fn kvm_getpcpu |
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| 62 | function returns a buffer holding the per-CPU data for a single CPU. |
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| 63 | This buffer is described by the |
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| 64 | .Vt "struct pcpu" |
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| 65 | type. |
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| 66 | The caller is responsible for releasing the buffer via a call to |
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| 67 | .Xr free 3 |
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| 68 | when it is no longer needed. |
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| 69 | If |
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| 70 | .Fa cpu |
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| 71 | is not active, then |
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| 72 | .Dv NULL |
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| 73 | is returned instead. |
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| 74 | .Sh CACHING |
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| 75 | These functions cache the nlist values for various kernel variables which are |
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| 76 | reused in successive calls. |
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| 77 | You may call either function with |
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| 78 | .Fa kd |
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| 79 | set to |
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| 80 | .Dv NULL |
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| 81 | to clear this cache. |
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| 82 | .Sh RETURN VALUES |
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| 83 | On success, the |
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| 84 | .Fn kvm_getmaxcpu |
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| 85 | function returns the maximum number of CPUs supported by the kernel. |
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| 86 | If an error occurs, |
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| 87 | it returns -1 instead. |
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| 88 | .Pp |
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| 89 | On success, the |
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| 90 | .Fn kvm_getpcpu |
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| 91 | function returns a pointer to an allocated buffer or |
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| 92 | .Dv NULL. |
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| 93 | If an error occurs, |
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| 94 | it returns -1 instead. |
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| 95 | .Pp |
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| 96 | If either function encounters an error, |
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| 97 | then an error message may be retrieved via |
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| 98 | .Xr kvm_geterr 3. |
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| 99 | .Sh SEE ALSO |
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| 100 | .Xr free 3 , |
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| 101 | .Xr kvm 3 |
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