.TH "libnvme_write_reg64" 9 "libnvme_write_reg64" "October 2026" "libnvme API manual" LINUX
.SH NAME
libnvme_write_reg64 \- Write a 64-bit controller register of a PCIe controller
.SH SYNOPSIS
.B "int" libnvme_write_reg64
.BI "(struct libnvme_transport_handle *hdl "  ","
.BI "__u32 offset "  ","
.BI "__u64 value "  ","
.BI "bool mmio32 "  ");"
.SH ARGUMENTS
.IP "hdl" 12
Transport handle
.IP "offset" 12
Offset of the register in bytes
.IP "value" 12
Value to write
.IP "mmio32" 12
Write the register as two 32-bit values, low half first.
Some devices do not support 64-bit MMIO.
.SH "DESCRIPTION"
\fIoffset\fP must be a multiple of 8. 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.