215 lines
4.8 KiB
HTML
215 lines
4.8 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of S390_STHYI</TITLE>
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</HEAD><BODY>
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<H1>S390_STHYI</H1>
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Section: System Calls (2)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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s390_sthyi - emulate STHYI instruction
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/asm/unistd.h">asm/unistd.h</A>></B>
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<B>int s390_sthyi(unsigned long </B><I>function_code</I><B>, void *</B><I>resp_buffer</I><B>,</B>
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<B> uint64_t *</B><I>return_code</I><B>, unsigned long </B><I>flags</I><B>);</B>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>s390_sthyi</B>()
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system call emulates the STHYI (Store Hypervisor Information) instruction.
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It provides hardware resource information for the machine and its
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virtualization levels.
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This includes CPU type and capacity, as well as the machine model and
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other metrics.
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<P>
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The
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<I>function_code</I>
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argument indicates which function to perform.
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The following code(s) are supported:
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<DL COMPACT>
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<DT id="1">0<DD>
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Return CP (Central Processor) and IFL (Integrated Facility for Linux)
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capacity information.
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</DL>
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<P>
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The
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<I>resp_buffer</I>
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argument specifies the address of a response buffer.
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When the
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<I>function_code</I>
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is 0, the buffer must be one page (4K) in size.
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If the system call returns 0,
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the response buffer will be filled with CPU capacity information.
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Otherwise, the response buffer's content is unchanged.
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<P>
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The
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<I>return_code</I>
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argument stores the return code of the STHYI instruction,
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using one of the following values:
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<DL COMPACT>
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<DT id="2">0<DD>
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Success.
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<DT id="3">4<DD>
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Unsupported function code.
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</DL>
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<P>
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For further details about
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<I>return_code</I>,
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<I>function_code</I>,
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and
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<I>resp_buffer</I>,
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see the reference given in NOTES.
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<P>
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The
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<I>flags</I>
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argument is provided to allow for future extensions and currently
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must be set to 0.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success (that is: emulation succeeded), the return value of
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<B>s390_sthyi</B>()
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matches the condition code of the STHYI instructions, which is a value
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in the range [0..3].
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A return value of 0 indicates that CPU capacity information is stored in
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<I>*resp_buffer</I>.
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A return value of 3 indicates "unsupported function code" and the content of
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<I>*resp_buffer</I>
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is unchanged.
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The return values 1 and 2 are reserved.
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<P>
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On error, -1 is returned, and
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<I>errno</I>
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is set appropriately.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="4"><B>EFAULT</B>
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<DD>
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The value specified in
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<I>resp_buffer</I>
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or
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<I>return_code</I>
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is not a valid address.
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<DT id="5"><B>EINVAL</B>
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<DD>
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The value specified in
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<I>flags</I>
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is nonzero.
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<DT id="6"><B>ENOMEM</B>
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<DD>
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Allocating memory for handling the CPU capacity information failed.
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<DT id="7"><B>EOPNOTSUPP</B>
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<DD>
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The value specified in
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<I>function_code</I>
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is not valid.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>VERSIONS</H2>
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This system call is available since Linux 4.15.
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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This Linux-specific system call is available only on the s390 architecture.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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Glibc does not provide a wrapper for this system call, use
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<B><A HREF="/cgi-bin/man/man2html?2+syscall">syscall</A></B>(2)
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to call it.
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<P>
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For details of the STHYI instruction, see
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the documentation page
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<P>
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When the system call interface is used, the response buffer doesn't
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have to fulfill alignment requirements described in the STHYI
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instruction definition.
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<P>
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The kernel caches the response (for up to one second, as of Linux 4.16).
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Subsequent system call invocations may return the cached response.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+syscall">syscall</A></B>(2)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="8"><A HREF="#lbAB">NAME</A><DD>
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<DT id="9"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="10"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="11"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="12"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="13"><A HREF="#lbAG">VERSIONS</A><DD>
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<DT id="14"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="15"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="16"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="17"><A HREF="#lbAK">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:34 GMT, March 31, 2021
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