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Geoffrey McRae gnif

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gnif /
Last active Jan 29, 2022
IBM branded APC SmartUPS 3000VA Notes

These are notes on modifications to make to the IBM branded 2RU APC SmartUPS 3000VA UPS to make it operate as a hybrid solar inverter/ups.

Disable the charging circuit

Since I am charging from solar I do not want the UPS to be able to charge the externally attached battery array, on this model this is very simply done by inserting a diode on the RED and BLACK wires coming from the front of the ups (charging module) to J4 on the main PCB to prevent reverse current flow to the batteries. The diode is required or the charging module wont be powerered at startup which puts the unit into a fault mode.

Coltrolling the output

Initially I was using a solid state relay to disconnect the feed in to the UPS when I was getting enough power to charge the batteries and run my equipment from solar, however this has been causing issues with RCDs (residual current devices) due to the massive inrush current when the UPS is re-connected to the supply. As such I have reverse engineered enough of the circuit to understa

gnif /
Created Aug 13, 2020
Generate the hex route rule for DHCP (pfSense)

Usage is simple:


Results: via = 18:c0:a8:0a:00:c0:a8:0a:01

gnif / Makefile
Last active Jan 12, 2020
Proof of concept: Create Pixmap via DRI3 from shared memory via udmabuf
View Makefile
gcc -D_GNU_SOURCE main.c -Wall -Werror -g -Og -o test -lX11-xcb -lX11 -lxcb -lxcb-dri3 -lxcb-present
gnif / main.c
Last active Jan 1, 2020
Example X11 application that uses XGetFrame to capture an application window.
View main.c
Example X11 application that uses XGetFrame to capture an application window.
Copyright 2020 Geoffrey McRae <>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
gnif /
Created Dec 19, 2019
HAProxy Galera Monitor Script
# Script to make a proxy (ie HAProxy) capable of monitoring Galera Cluster nodes properly
# Updated by Geoffrey McRae to check for MySQL command failure, and renamed to 'Galera Cluster'
# Author: Olaf van Zandwijk <>
# Author: Raghavendra Prabhu <>
# Author: Geoffrey McRae <>
# Documentation and download:
gnif / main.c
Last active Oct 31, 2019
Example client for the new zero-copy shared ram device @
View main.c
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/stat.h>
typedef struct {
gnif /
Last active Oct 6, 2019
Some bash helper functions for launching QEMU guests directly
allocateRAM $NODE $RAM
takeDevByName "\[AMD/ATI\] Navi 10 (rev c1)" 1
gnif /
Created Apr 26, 2019
Direct spool HPGL to a Roland DXY-1100 (Likely works with other models too)
# - HPGL Spooler for Serial attached Roland DXY-1100
# Copyright (C) 2019 Geoffrey McRae <>
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
gnif / vega-10-reset.c
Last active Jul 2, 2020
Experimental NON FUNCTIONAL vega 10 reset
View vega-10-reset.c
static int reset_amdgpu_vega(struct pci_dev *dev, int probe) {
#define MP0_BASE 0x16000
#define mmMP0_SMN_C2PMSG_33 ((MP0_BASE + 0x0061) * 4)
#define mmMP0_SMN_C2PMSG_64 ((MP0_BASE + 0x0080) * 4)
#define mmMP0_SMN_C2PMSG_81 ((MP0_BASE + 0x0091) * 4)
resource_size_t rmmio_base, rmmio_size;
void __iomem *rmmio;
int ret;
gnif /
Created Nov 3, 2018
[BASH] Convert bytes to human readable
function bytesToHR()
local SIZE=$1
local UNITS="B KiB MiB GiB TiB PiB"
for F in $UNITS; do
local UNIT=$F
test ${SIZE%.*} -lt 1024 && break;
SIZE=$(echo "$SIZE / 1024" | bc -l)