From 9c6897e848933b1cb256416987c55d0a12f6e3bd Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sat, 23 Dec 2017 04:45:22 +0100
Subject: [PATCH] arch(3): document #P/realmodemem file

---
 sys/man/3/arch | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sys/man/3/arch b/sys/man/3/arch
index fd28462ad..621836353 100644
--- a/sys/man/3/arch
+++ b/sys/man/3/arch
@@ -15,6 +15,7 @@ arch \- architecture-specific information and control
 .B /dev/iow
 .B /dev/irqalloc
 .B /dev/msr
+.B /dev/realmodemem
 .SH DESCRIPTION
 This device presents textual information about PC hardware and allows
 user-level control of the I/O ports on x86-class machines.
@@ -129,6 +130,12 @@ Reads and writes to
 .I msr
 go to the P4/P6/Core/Core2/AMD64 MSRs.
 .PP
+The
+.I realmodemem
+file provides access to the first megabyte of memory. This
+allows reading BIOS data structures and option ROMs.
+Writing is limited to the VGA framebuffer at [0xA0000-0xBFFFF].
+.PP
 Reads and writes to
 .I ec
 transfer bytes from and to the embedded controller.