Posts Tagged ‘BIOS’

Further Soekris net6501 improvements for OpenBSD

Thursday, April 30th, 2015

The release of OpenBSD 5.7 brings the latest batch of improvements I made for Soekris net6501 users.

The first change adds platform detection that should in fact work on all Soekris boards, (I think this change actually went in circa 5.4 but I never posted about it). Normally this information comes via the SMBIOS extensions but Soekris boards have a much stripped-down BIOS that lacks any of this support. There are however some vendor and product strings embedded in the BIOS image (probably used for printing on the serial console at POST) so they get picked out and used. For example:

# sysctl hw.vendor hw.product
hw.vendor=Soekris Engineering
hw.product=net6501

The second change adds the skgpio(4) driver which provides access to the GPIO & LEDs on the net6501. Two GPIO devices are provided; gpio0 for the 16 real GPIO pins, (JP8 in the net6501 manual); and gpio1 for the error and ready LEDs coerced into the GPIO framework as output-only pins. Here is what is displayed in dmesg at boot:

skgpio0 at isa0 port 0x680/32                                                  
gpio0 at skgpio0: 16 pins                                                      
gpio1 at skgpio0: 2 pins

You still need to configure the GPIO pins prior to raising the securelevel so add the following to /etc/rc.securelevel as a minimum:

gpioctl -q gpio1 0 set out error_led
gpioctl -q gpio1 1 set out ready_led

Now once the system is booted you can toggle the error LED with the following:

# gpioctl gpio1 error_led 2
pin error_led: state 0 -> 1
# gpioctl gpio1 error_led 2
pin error_led: state 1 -> 0

Soekris CPU Scaling and OpenBSD 5.2

Tuesday, December 25th, 2012

OpenBSD 5.2 was released nearly two months ago and I had forgotten to upgrade my Soekris net6501, apart from my driver now being part of the kernel, this release also added support to the SpeedStep frequency scaling driver for the Atom CPU.

The simple benchmark to keep in mind is using the md5(1) command, using its built-in time trial test. Under the previous OpenBSD 5.1 release:

# md5 -ttt
MD5 time trial.  Processing 1000000 10000-byte blocks...
Digest = f0843f04c524250749d014a8152920ec
Time   = 124.227876 seconds
Speed  = 80497230.750367 bytes/second

You can see I’m getting roughly 80 MB/s. Now upgrade to OpenBSD 5.2 and repeat the test, you’ll get pretty much the same speeds, however now we have the CPU frequency scaling to play with. The scaling is very coarse, the only two speeds supported are 600 MHz and whatever maximum the CPU supports, so in my case with a net6501-70, it’s 1.6 GHz. To change the scaling simply manipulate the hw.setperf sysctl(8) variable.

By default the CPU is running at 100%, confirmed by:

# sysctl hw.setperf
hw.setperf=100

Now set the CPU frequency to the slowest speed:

# sysctl hw.setperf=0
hw.setperf: 100 -> 0

Now running the test again I get the following results:

# md5 -ttt
MD5 time trial.  Processing 1000000 10000-byte blocks...
Digest = f0843f04c524250749d014a8152920ec
Time   = 123.948587 seconds
Speed  = 80678612.334645 bytes/second

Almost exactly the same speed, which doesn’t make sense given I’ve knocked 1 GHz off the clock speed! So put the CPU back to 100% and try again:

# sysctl hw.setperf=100
hw.setperf: 0 -> 100
# md5 -ttt
MD5 time trial.  Processing 1000000 10000-byte blocks...
Digest = f0843f04c524250749d014a8152920ec
Time   = 46.424699 seconds
Speed  = 215402581.285449 bytes/second

Ah-ha, about 210 MB/s this time! It transpires there’s a bug in the Soekris BIOS, despite advertising the CPU as 1.6 GHz it wasn’t programmed correctly and was only being clocked at 600 MHz, so all this time I’ve effectively had the base net6501-30 model albeit with the extra RAM. You can work around this by setting hw.setperf to 100 on each boot.

A new BIOS 1.41c has been released which fixes this issue and programs the CPU to run at its advertised maximum speed. However to upgrade to this involves my eternal battle with serial terminal software and uploading over XMODEM which is notoriously fickle, although I think I have it cracked…

I usually use a Mac OS X host with a KeySpan USB/Serial adapter to connect to the net6501 so I already have tools like cu(1) and screen(1). You’ll also need the lrzsz tools installed which if using MacPorts is as easy as:

# sudo port install lrzsz

Using cu(1), connect to the Soekris:

# sudo cu -l /dev/tty.KeySerial1 -s 19200

Power the board on, use Ctrl+P to break into the BIOS monitor and type download to start the Soekris waiting to receive over XMODEM. Now you need to type ~+sz -X /path/to/b6501_141c.bin, possibly as quickly as you can after the previous command. If that works, type flashupdate afterwards to reprogram the BIOS. You’ll get something like the following transcript:

> download
 
Start sending file using XMODEM/CRC protocol.
~+sz -X /path/to/b6501_141c.bin
Sending /path/to/b6501_141c.bin, 1982 blocks: Give your local XMODEM receive command now.
Bytes Sent: 253696   BPS:1746                            
 
Transfer complete
 
File downloaded succesfully, size 253696 Bytes.
 
> flashupdate
Updating BIOS Flash ,,,,,,,,,,,,, Done.
 
> reboot

Reboot and boot back into OpenBSD. Now the time trial should return a result of roughly 210 MB/s every time. Because I obviously don’t need 1.6 GHz of CPU all time, I’ve enabled the apmd(8) daemon which manipulates the hw.setperf variable based on the CPU idle time. Add the following to /etc/rc.conf.local:

apmd_flags="-C -f /dev/null"

The -f is only necessary when running i386 otherwise apmd(8) complains. Start with:

# /etc/rc.d/apmd start
apmd(ok)

Normally hw.setperf will be 0 however when you do something CPU-intensive (such as the MD5 time trial) apmd(8) will automatically adjust hw.setperf back to 100 so you still get the 210 MB/s result, but most of the time you’ll have lower power draw and less heat.