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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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s390_sthyi(2) System Calls Manual s390_sthyi(2)
s390_sthyi - emulate STHYI instruction
Standard C library (libc, -lc)
#include <asm/sthyi.h> /* Definition of STHYI_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_s390_sthyi, unsigned long function_code,
void *resp_buffer, uint64_t *return_code,
unsigned long flags);
Note: glibc provides no wrapper for s390_sthyi(), necessitating
the use of syscall(2).
The s390_sthyi() system call emulates the STHYI (Store Hypervisor
Information) instruction. It provides hardware resource
information for the machine and its virtualization levels. This
includes CPU type and capacity, as well as the machine model and
other metrics.
The function_code argument indicates which function to perform.
The following code(s) are supported:
STHYI_FC_CP_IFL_CAP
Return CP (Central Processor) and IFL (Integrated Facility
for Linux) capacity information.
The resp_buffer argument specifies the address of a response
buffer. When the function_code is STHYI_FC_CP_IFL_CAP, the
buffer must be one page (4K) in size. If the system call returns
0, the response buffer will be filled with CPU capacity
information. Otherwise, the response buffer's content is
unchanged.
The return_code argument stores the return code of the STHYI
instruction, using one of the following values:
0 Success.
4 Unsupported function code.
For further details about return_code, function_code, and
resp_buffer, see the reference given in NOTES.
The flags argument is provided to allow for future extensions and
currently must be set to 0.
On success (that is: emulation succeeded), the return value of
s390_sthyi() matches the condition code of the STHYI
instructions, which is a value in the range [0..3]. A return
value of 0 indicates that CPU capacity information is stored in
*resp_buffer. A return value of 3 indicates "unsupported
function code" and the content of *resp_buffer is unchanged. The
return values 1 and 2 are reserved.
On error, -1 is returned, and errno is set to indicate the error.
EFAULT The value specified in resp_buffer or return_code is not a
valid address.
EINVAL The value specified in flags is nonzero.
ENOMEM Allocating memory for handling the CPU capacity
information failed.
EOPNOTSUPP
The value specified in function_code is not valid.
Linux on s390.
Linux 4.15.
For details of the STHYI instruction, see the documentation page
⟨https://www.ibm.com/support/knowledgecenter/SSB27U_6.3.0/com.ibm.zvm.v630.hcpb4/hcpb4sth.htm⟩.
When the system call interface is used, the response buffer
doesn't have to fulfill alignment requirements described in the
STHYI instruction definition.
The kernel caches the response (for up to one second, as of Linux
4.16). Subsequent system call invocations may return the cached
response.
syscall(2)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-05-02 s390_sthyi(2)
Pages that refer to this page: syscalls(2)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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