.TH "libnvme_read_regs" 9 "libnvme_read_regs" "October 2026" "libnvme API manual" LINUX
.SH NAME
libnvme_read_regs \- Read the controller registers of a PCIe controller
.SH SYNOPSIS
.B "int" libnvme_read_regs
.BI "(struct libnvme_transport_handle *hdl "  ","
.BI "__u32 offset "  ","
.BI "void *buf "  ","
.BI "__u32 len "  ");"
.SH ARGUMENTS
.IP "hdl" 12
Transport handle
.IP "offset" 12
Offset of the first register in bytes
.IP "buf" 12
Buffer to store the register values
.IP "len" 12
Number of bytes to read
.SH "DESCRIPTION"
Copies the register range [\fIoffset\fP, \fIoffset\fP + \fIlen\fP) of the controller
into \fIbuf\fP, using 32-bit MMIO reads. The register values are stored in
little-endian byte order, as they appear in the register map. \fIoffset\fP
and \fIlen\fP must be multiples of 4 and the range must be within the first
4 KiB of the register map.

This should only be sent to controller handles, not to namespaces.
.SH "RETURN"
0 on success or a negative error code otherwise. -ENOTSUP
indicates that the transport has no memory-mapped registers.