|S390_STHYI(2)||System Calls Manual||S390_STHYI(2)|
int s390_sthyi(unsigned long function_code, void *resp_buffer, uint64_t *return_code, unsigned long flags);
Note: There is no glibc wrapper for this system call; see NOTES.
The function_code argument indicates which function to perform. The following code(s) are supported:
- 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 0, 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:
- 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 error, -1 is returned, and errno is set to indicate the error.
- The value specified in resp_buffer or return_code is not a valid address.
- The value specified in flags is nonzero.
- Allocating memory for handling the CPU capacity information failed.
- The value specified in function_code is not valid.
For details of the STHYI instruction, see the documentation page.
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.
|2021-03-22||Linux Programmer's Manual|