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s390_pci_mmio_write, s390_pci_mmio_read - transfer data to/from PCI MMIO memory page
#include <sys/syscall.h> /* Definition of SYS_* constants */ #include <unistd.h> int syscall(SYS_s390_pci_mmio_write, unsigned long mmio_addr, const void *user_buffer, size_t length); int syscall(SYS_s390_pci_mmio_read, unsigned long mmio_addr, void *user_buffer, size_t length); Note: glibc provides no wrappers for these system calls, necessitating the use of syscall(2).
The s390_pci_mmio_write() system call writes length bytes of data from the user-space buffer user_buffer to the PCI MMIO memory location specified by mmio_addr. The s390_pci_mmio_read() system call reads length bytes of data from the PCI MMIO memory location specified by mmio_addr to the user-space buffer user_buffer. These system calls must be used instead of the simple assignment or data-transfer operations that are used to access the PCI MMIO memory areas mapped to user space on the Linux System z platform. The address specified by mmio_addr must belong to a PCI MMIO memory page mapping in the caller's address space, and the data being written or read must not cross a page boundary. The length value cannot be greater than the system page size.
On success, s390_pci_mmio_write() and s390_pci_mmio_read() return 0. On failure, -1 is returned and errno is set to indicate the error.
EFAULT The address in mmio_addr is invalid. EFAULT user_buffer does not point to a valid location in the caller's address space. EINVAL Invalid length argument. ENODEV PCI support is not enabled. ENOMEM Insufficient memory.
These system calls are available since Linux 3.19.
This Linux-specific system call is available only on the s390 architecture. The required PCI support is available beginning with System z EC12.
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