Incoherent ramblings

Configuring wireless on a RHEL7 NUC6i5SYH

April 26, 2016 Incoherent ramblings , , ,

I don’t currently have ethernet lines running to my new office space.  The NUC does have builtin wireless, but doesn’t appear functional in the linux 3.10 kernel that is installed by default on RHEL7


#  lspci -nn | grep -n net
00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection I219-V [8086:1570] (rev 21)

01:00.0 Network controller [0280]: Intel Corporation Wireless 8260 [8086:24f3] (rev 3a)

#  grep -i 8086.*24f3 /lib/modules/*/modules.alias

alias pci:v00008086d000024F3sv*sd00000010bc*sc*i* iwlwifi

#  lsmod | grep wifi
# [nothing]

I can load it explicitly by doing:

#  modprobe iwlwifi

iwlwifi               112501  0 

cfg80211              514740  1 iwlwifi

but the NetworkManager doesn’t see the interface. Running ‘systemctl restart NetworkManager’ doesn’t help.

If I switch to the 4.5 kernel and install the latest iwlwifi firmware I’m able to get things up and running:

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
yum -y install yum-plugin-fastestmirror
yum --enablerepo=elrepo-kernel install kernel-ml

git clone https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
cp linux-firmware/iwlwifi*.ucode /lib/firmware/

After boot, I get dmesg errors from the iwlwifi driver:

# dmesg | grep wifi

[    2.612790] iwlwifi 0000:01:00.0: enabling device (0000 -> 0002)

[    2.618136] iwlwifi 0000:01:00.0: Unsupported splx structure

[    2.619632] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-20.ucode failed with error -2

[    2.619635] iwlwifi 0000:01:00.0: Falling back to user helper

[   63.005134] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-19.ucode failed with error -2

[   63.005137] iwlwifi 0000:01:00.0: Falling back to user helper

[  122.981747] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-18.ucode failed with error -2

[  122.981751] iwlwifi 0000:01:00.0: Falling back to user helper

[  182.977468] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-17.ucode failed with error -2

[  182.977472] iwlwifi 0000:01:00.0: Falling back to user helper

The firmware copied from linux-firmware had version: iwlwifi-8000C-21.ucode which is newer than the any of the ones in the failed to load messages. I wonder if that splx structure error is from attempting to load 8000C-21?

It turns out that the user mode driver works, but you have to be really patient. A number of minutes after boot it kicks in, which can be seen by the mac80211 driver now running:

# lsmod | grep wifi

iwlwifi               139264  1 iwlmvm

cfg80211              577536  3 iwlwifi,mac80211,iwlmvm

I then also see the following additional dmesg log points from the wifi driver:


# dmesg | grep iwlwifi

[  122.544157] iwlwifi 0000:01:00.0: Falling back to user helper

[  182.549189] iwlwifi 0000:01:00.0: loaded firmware version 17.254495.0 op_mode iwlmvm

[  182.557558] iwlwifi 0000:01:00.0: Detected Intel(R) Dual Band Wireless AC 8260, REV=0x208

[  182.557910] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled

[  182.558824] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled

[  182.559866] iwlwifi 0000:01:00.0: can't access the RSA semaphore it is write protected

[  182.707622] iwlwifi 0000:01:00.0 wlp1s0: renamed from wlan0

[  182.719296] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled

[  182.719562] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled

[  182.720422] iwlwifi 0000:01:00.0: can't access the RSA semaphore it is write protected

[  182.855388] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled

[  182.855958] iwlwifi 0000:01:00.0: L1 Enabled - LTR Enabled


[  182.857102] iwlwifi 0000:01:00.0: can't access the RSA semaphore it is write protected

At this point the wifi connection shows up in the NetworkManager, and I’m able to configure the WPA password, giving me a wlp1s0 interface configured and available for use.

Did “Canada” stop bringing peace to Syria by bombing them?

March 10, 2016 Incoherent ramblings , , , , ,

March 10, 2016

Dear Prime Minister Trudeau,

My wife got caught up in the “hope and change” type propaganda associated with your campaign, but I was more cynical. I was, however, pleasantly surprised when you announced that Canada would no longer be bombing Syria. I would actually say that I was shocked and surprised that a Canadian politician had some sanity.

Needless to say, it wasn’t surprising to me that you later back-pedalled on this, and announced that “Canada” would continue to bomb Syria until Feb 22, 2016 [1, 2], apparently acting on the instructions of your handlers in Davos. The fact that this is done while simultaneously posing for photo ops with Syrian refugees and claiming that “Canada welcomes refugees” is particularly repugnant. My faith in the status quo of Canadian politics is nicely restored by your lack of action and backbone.

It is now well past Feb 22, but I have not seen any media suggesting that you have followed through on your watered down promise of less future belligerence. This could be a failing of the media, in particular, the CBC, which appears to be solidly in the pockets of armaments industry, reporting idiocy like “Most Canadians disagree” that we should continue to bring peace and solve the Syrian refugee outflux by bombing them [3]. Can you please confirm or deny whether you did limit “our” peacekeeping to one additional month of bombing.

Sincerely,

Peeter Joot

[1] http://www.cbc.ca/news/politics/isis-bombing-cf-18s-trudeau-milewskie-1.3416472
[2] http://www.cbc.ca/news/politics/justin-trudeau-canada-isis-fight-announcement-1.3438279
[3] http://www.cbc.ca/news/politics/canada-fighter-jets-isis-poll-1.3437288

A copy of this letter and any responses will be made available on the internet for public comment.

Survey: Are there any additional comments you would like to add about your graduate student experience at this university?

February 8, 2016 Incoherent ramblings

I definitely enjoying the formal study of the courses I am taking, however, I find University courses inferior to self study in many ways. There are two specific benefits to a University course:

1) Having a knowledgeable instructor at hand to answer questions.
2) Having that same knowledge base available to set the study curriculum, since that instruction can direct attention to the most important aspects of the study.

The fixed formal lecture format is not terribly effective, at least for the scientific topics that I have been studying. In this day and age, when the technology to record lectures is so pervasive and freely available, there is really no excuse for the formal and fixed lecture style still found in the classroom. In an ideal learning environment, there would be time available between concepts to work through problems and gain complete understanding of each idea before going on to the next. Such an ideal learning environment would interleave practical work, text study and lectures. Testing should be used as a metric for whether or not the material is fully understood before continuing to the next aspect of study (or returning to areas of deficiency). In University classes testing is designed to produce a grade, not understanding, something that is completely backwards.

I am also surprised to see that grading for many graduate courses is still primarily based on exams. Having spent twenty years working before coming back to school it is a rude shock to come back to such an artificial metric for success. In nowhere other but school is it considered reasonable to make the metric for success based on how quickly a student can rush through a test, with no references at hand, attempting to construct answers that are optimized for maximal marks. In industry, the kind of mistakes that are inevitable in an examination context would lead to millions of dollars of service and product maintenance costs, and get people fired.

It is asinine that there is no feedback mechanism in place to review and retest of failed or partially successful final exam material. This seems to highlight the fact that university courses do not seem to be designed with learning as the primary goal. It is not clear what that goal is.

Air duct cleaning telemarketing call: not sure if he gave up or was confused?

January 12, 2016 Incoherent ramblings ,

Am working from home with snow on the roads making the commute look unappealing.  Had the pleasure of a brief playtime with a telemarketer

Hello, may I speak to the homeowner please?

Me: who is this?

This is Suresh from “Air Duct Cleaners”

Me: I’m sorry, I don’t have any ducks to clean.  They swim away every time I try to clean them.

Suresh: I’m sorry.  Have a nice day [click].

He didn’t stay on the line to play with me 🙁

provisional M.Eng study plan

January 2, 2016 Incoherent ramblings

I’m trying to plot out a potential sequence for the remainder of my M.Eng courses. Most of the physics courses only run in the fall, and I still have to take a few more engineering courses to meet the requirements for the program. The following sequence, starting with the courses I’ve taken or am now enrolled on, gets one interesting course into each time slot:

My plan for the rest of the program is currently:

 

I’m hoping that the ECE Introduction to Computational Electrodynamics course will run again, and if it does I’ll switch things up to accomodate it.