Code Golfing a “Is Power of Two?” Function

Instead of looping around, there’s a simpler way.

diff –git a/kernel/elf.cpp b/kernel/elf.cpp
index 8bee7c5..ca2d50c 100644
— a/kernel/elf.cpp
+++ b/kernel/elf.cpp
@@ -42,12 +42,9 @@
namespace Sortix {
namespace ELF {

-static bool is_power_of_two(uintptr_t value)
+static bool is_power_of_two(uintptr_t x)
– for ( uintptr_t i = 0; i < sizeof(uintptr_t) * 8; i++ )
– if ( (uintptr_t) 1 << i == value )
– return true;
– return false;
+ return (x != 0) && ((x & (x – 1)) == 0);

The code in question is found in the excellent hobby OS sortix.

macOS – Running Steam Games on a Case–Sensitive Machine

Unfortunately, when you try running certain games on a mac, on a case sensistive HFS+ filesystem, you might hit a roadblock.

Steam itself will run fine.

Fortunately there is a solution by using OpenZFS. I won’t go into the details of installing ZFS on a mac as there is plenty of information out there. I simply use homebrew for that kind of thing. Refer to the OpenZFS Wiki, they have instructions on how to install using homebrew.

Method for Creating the Filesystem Image

OpenZFS supports creating a pool inside a file, so this is what we are going to do.

mkfile -n 5g steam_disk.zfs
zpool create -O casesensitivity=insensitive steam_pool /Users/$USER/steam_disk.zfs

Then you will get a shiny new volume with the required properties under /Volumes/steam_pool/. Fire up Steam, tell it to install there.

Enjoy, and don’t forget to read up on ZFS basics if you don’t know how to export and import a pool.

zpool export steam_pool
zpool import -d /Users/$USER/ -a

Adjusting Intel Graphics Brightness in FreeBSD

There are various ways of adjusting the brightness on laptop panels. If you are running the correct Intel driver, it should be a matter of poking around the sysctl’s.

~% sysctl -a | grep lcd 100 100 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 100 100 60 0

From that we know that the correct one to adjust is lcd0.brightness.

~% sudo sysctl

Add NetBSD Support for AboCom RTL8188EU

I’m running Linux. Follow the instructions from Cross building NetBSD on Linux:

===> Successful make release
===> ended: Fri Nov 4 12:38:00 EDT 2016
===> Summary of results: command: ./ -U -u -m amd64 release started: Fri Nov 4 10:17:30 EDT 2016
NetBSD version: 7.0.2
MACHINE: amd64
Build platform: Linux 4.8.6-1-ARCH x86_64
HOST_SH: /usr/bin/sh
MAKECONF file: /etc/mk.conf (File not found)
TOOLDIR path: /home/sinetek/dev/building-netbsd/usr/src/obj/tooldir.Linux-4.8.6-1-ARCH-x86_64
DESTDIR path: /home/sinetek/dev/building-netbsd/usr/src/obj/destdir.amd64
RELEASEDIR path: /home/sinetek/dev/building-netbsd/usr/src/obj/releasedir
Updated makewrapper: /home/sinetek/dev/building-netbsd/usr/src/obj/tooldir.Linux-4.8.6-1-ARCH-x86_64/bin/nbmake-amd64
Successful make release ended: Fri Nov 4 12:38:00 EDT 2016
===> .

Then we build a custom configuration file for the kernel.
Drat. The config file for GENERIC already includes urtwn.
Let’s see what we can do poking around. Let’s grab the device id from Linux.

$ lsusb
Bus 001 Device 009: ID 07b8:8179 AboCom Systems Inc

Let’s poke around the driver. I found something interesting in if_urtwn.c.
From /sys/dev/usb/usbdevs.h I see that the constants I want are ABOCOM, and REALTEK RTL8188EU.
Let’s add these in.

diff –git a/sys/dev/usb/if_urtwn.c b/sys/dev/usb/if_urtwn.c
index 379365e..3294e54 100644
— a/sys/dev/usb/if_urtwn.c
+++ b/sys/dev/usb/if_urtwn.c
@@ -167,6 +167,7 @@ static const struct urtwn_dev {
#undef URTWN_DEV
#undef URTWN_RTL8188E_DEV

… and the usbdevs:

diff –git a/sys/dev/usb/usbdevs b/sys/dev/usb/usbdevs
index bfe82a2..1bc213f 100644
— a/sys/dev/usb/usbdevs
+++ b/sys/dev/usb/usbdevs
@@ -640,6 +640,7 @@ product ABOCOM XX9 0x4104 XX9
product ABOCOM UFE2000 0x420a UFE2000 USB2.0 Fast Ethernet Adapter
product ABOCOM WL54 0x6001 WL54
product ABOCOM RTL8192CU 0x8178 RTL8192CU
+product ABOCOM RTL8188EU 0x8179 RTL8188EU
product ABOCOM RTL8188CU_1 0x8188 RTL8188CU
product ABOCOM RTL8188CU_2 0x8189 RTL8188CU
product ABOCOM XX10 0xabc1 XX10

Regenerate the correct usb dev headers.

$ TOOL_AWK=awk bmake -f Makefile.usbdevs usbdevs.h

Rebuild the kernel, then rebuild the iso image:

./ -U -u -m amd64 release
./ -U -u -m amd64 iso-image

Test. Mad Success!!

Flashing the Arduino Due (SAM3X) Under FreeBSD, TrueOS

This post is solely concerned with the task of flashing a binary on the Arduino Due. While the Arduino software is great, I like having more control over low-level details.

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU. For more information please see the official site.

The board itself has two programming ports. One of them is called the “native” port and is connected directly to the Atmel SAM3X chip. This has a few implications; if a program is already running, the USB port might not be in bootloader mode.

Programming Method

Connect the Arduino Due via the native port. Push the **ERASE** button.
The chip will now default to a programming mode.

Using Bossac

You should have bossac installed on your system. Let’s probe the chip.

~% sudo bossac -i
Device found on cuaU0
Atmel SMART device 0x285e0a60 found
Device : ATSAM3X8
Chip ID : 285e0a60
Version : v1.1 Dec 15 2010 19:25:04
Address : 524288
Pages : 2048
Page Size : 256 bytes
Total Size : 512KB
Planes : 2
Lock Regions : 32
Locked : none
Security : false
Boot Flash : false

The internal flash is 512KB. Let’s try writing a file.

sudo bossac -e -w -b=1 512k_file_input

Read back the chip, comparing the files, it should be the same.

sudo bossac -r 512k_file_output

Run the basic check.

[sinetek@SEATK0] ~% sha256 512k_file_input 512k_file_output
SHA256 (512k_file_input) = 3d338d950950054ec0d83191ce5e00ed067190af67c2a6eb41547a4bcf3ef1e0
SHA256 (512k_file_output) = 3d338d950950054ec0d83191ce5e00ed067190af67c2a6eb41547a4bcf3ef1e0

That is it for today. In the next installment we’ll make a little blinkylight demo, which will be more exciting!

Getting All 32C3 Presentations at Once

This little script might prove useful for those wishing to get the whole series of presentations for that year’s CCC.

for x in `lynx –dump | grep “http” | grep “32c3” | cut -c 7-`; do
parameter=”$parameter -O $x.torrent”;
curl $parameter;

I can’t remember who I got this from, but thank you in any case!

Edit: This is not condoned anymore, use the HTTP mirrors to download directly.

10.13 (17A264c) NVMe Driver: Poking Around

I wanted to see if the updated NVMe kext in 10.13 (build 17A264c) loads under Sierra. Here is the answer.

$ sudo kextutil IONVMeFamily.kext
(kernel) kxld[]: The super class vtable ‘__ZTV18IOTimerEventSource’ for vtable ‘__ZTV21AppleNVMeRequestTimer’ is out of date. Make sure your kext has been built against the correct headers.
(kernel) kxld[]: The super class vtable ‘__ZTV18IOTimerEventSource’ for vtable ‘__ZTV21AppleNVMeRequestTimer’ is out of date. Make sure your kext has been built against the correct headers.
(kernel) kxld[]: The super class vtable ‘__ZTV18IOTimerEventSource’ for vtable ‘__ZTV21AppleNVMeRequestTimer’ is out of date. Make sure your kext has been built against the correct headers.
(kernel) Can’t load kext – link failed.
(kernel) Failed to load executable for kext
(kernel) Kext failed to load (0xdc008016).
(kernel) Failed to load kext (error 0xdc008016).
Failed to load IONVMeFamily.kext – (libkern/kext) link error.
Check library declarations for your kext with kextlibs(8).