Linux on Asus R541U

    This is my experience with openSUSE Linux LEAP 15.0 on the Asus R541UA-RS51 laptop.  (Note: memtest identifies this computer as X541UAK / U3E1.)  Things in parenthesis are what Windows reports with Device Manager.

Hardware Components
Status under Linux
Notes
Intel Core i5-7200UProcessor 2.5GHz (up to 3.1GHz) 3M Cache Works

Display: BOE 15.6inch FHD (1920 x 1080) Works
Roughly 141 DPI
Intel HD graphics 620
Works

8GB DDR4 RAM Works
Toshiba 1TB 5400RPM Hard Drive
Works Upgraded to Seagate Hybrid Laptop 1TB
Realtek RTS5286 PCI Express Card Reader (for SD cards)
Works

DVD Drive: 8X Super Multi w/ DL ("HL-DT-ST DVD-RAM")
Works

Realtek RTL8723BE PCIe Wireless Network Adapter
Works

IMC Networks Video Cam ("VGA UVC Webcam")
Works

USB: one 3.0, one 2.0, and one USB-C 3.1 port
Works
Fast charge works even with stock kernel.
36WHrs 3-cell Li-ion Battery Pack Works
Provides roughly 4 hrs
Intel High Def. Audio  9d71 (rev 21) Realtech ALC256
Works*
Works
ELAN Touchpad ("Asus Precision")
Works

Realtek RTL8101/2/6E PCIE Fast/Gigabit Ethernet controller
Works

Asus keyboard
Works; slight nuissances
Number lock keeps engaging; no on-screen status program
Realtech Bluetooth 4.0
Unsure
Doesn't work
Intel Sunrise Chipset, Power Management
Works


asus2

Physical Fit and Finish

    This laptop is beautiful on the outside.  However, there are a few problems that might concern people who want to modify and/or upgrade this laptop.
    First, there are no "maintenance panels" on the bottom, which means that upgrades and maintenance require the keyboard to be removed.  You first remove all screws from the bottom of the laptop, then gently and carefully pry the keyboard surface (because the keyboard is built into the upper surface) off.

asus1

    Second, there seems to be no way to upgrade the RAM.  I have not yet felt the need to remove the motherboard to look at the bottom of it for expansion capabilities.  The hard drive can be upgraded fairly easily, once you pull up the keyboard.
    Third, unlike other laptops, the battery is built inside the laptop rather than externally, so (again) to replace it, you must pull up the keyboard.  The stock battery seems to give 4 hours of life in total (based on Linux estimates), but you should not, in theory, go past 50% if you want the battery to remain healthy longer, so you might want to consider getting an external power source for long trips.
    So it's beautiful, until you need to work on it.  Then it's not fun.
    Note that this laptop comes with Windows 10, a TPM module, and Secure Boot.  You do NOT get installation media: I strongly recommend making a disk image before you boot this laptop for the very first time.  Also, Fedora and OpenSUSE can handle Secure Boot (as can other Linux distributions), but why bother with Secure Boot?  It will only make upgrading the kernel a nuisance.  You would have to pay to upgrade Windows 10 to a version that has disk encryption to make the laptop fully and truly secure, otherwise Secure Boot is just another small hurdle for a thief to jump in order to steal your information.  So in my opinion, if you want ultimate security, either disable Secure Boot and install Linux in a way in which encryption will be enabled (LUKS XTS 256, baby) so you can protect your documents, or upgrade Windows 10.  If you enable Windows 10 encryption (not free), you'd probably end up only sharing files between operating systems using the SD card reader or USB devices, which can have drawbacks.  So again, my opinion is disable secure boot. You can always enable it later, in theory.

Linux DD
            LZMA Backup

Installation of OpenSUSE LEAP 15.0

    Installation was easy.  For the previous version of openSUSE, see this link.
    First, I wanted a Seagate Hybrid drive, so I did not boot the laptop with the original factory drive.  See the previous article for how I performed this.
    Then I popped in the OpenSUSE LEAP 15.0 install media (whatever is current as of 22 October 2017) and installed.  I used the instructions from Tweak Hound, and it worked perfectly.  I had previously shrank my windows partition down to about 150GB.
    See below for how I compile a kernel.  I am currently running OpenSUSE LEAP 15.0 with the stock kernel.

Using OpenSUSE LEAP 15.0

    First, I noticed that my logs filled up with error messages similar to these about AER ePCI errors.  Adding pci=noaer to the kernel command line seemed to fix that.
    Notice that on my last laptop, when you issued a command to suspend to RAM, the laptop would remain off until a lid up switch signal was given (i.e. if you tapped on the keyboard, it would not come out of suspend: only closing the lid, then re-opening the lid would solve this problem).  This laptop works fine: tapping on the keyboard will bring it out of suspend.  Also, the stock suspend key on the keyboard (once you tell XFCE which keyboard you have) works out of the box.
    Note that the speakers on this laptop are very loud and sound great, in general.
    As for USB support, note that there's a 2.0, 3.0, and 3.1 port.  The USB 2.0 port is nearest the laptop user.  Fast charging a cell phone with USB-C works even in Linux, but it requires you to use a USB-C to USB-C cable from the 3.1 port to your cell phone.  When you do this, it "just works", without any configuration required, unlike Windows which has an Asus app that allows you to enable or disable fast charge.  The power outputs seem to be dependent upon system state: i.e. if the laptop is on, USB-C power outputs are always on, and thus will fast charge any USB-C device that supports this.
    My solution for using two USB hard drives at the same time (due to having a 3.0 and 2.0 port) is to use a USB-C to 3.0 adapter and then putting the two hard drives on 3.0 ports.  I tend to reserve the 2.0 port for a USB mouse or something that has low data usage.

Annoying Behavior on OpenSUSE LEAP 15.0

    Bluetooth doesn't work with OpenSUSE's stock kernel.  When I updated the kernel it began to work.  You can disable Bluetooth separately from wireless LAN, which is a plus.  On my old laptop, you couldn't do this separately.
    The keyboard has a hybrid laptop/desktop layout with a numeric keyboard section.  However, the end key is on the numeric portion.  When typing, the number lock comes on, causing the end key to function as a "1".  I am constantly turning off the number lock in OpenSUSE, even in the new kernel, and even though I've configured the keyboard models and such.  I may need to do more testing to figure out why it's behaving this way.  Also, there's no on-screen application for XFCE that I can find that will display the status of the number lock on screen.  In addition, I have set "no" or "off" to the only number lock related setting in the sysconfig editor, and that results in the computer booting up with the number lock off, but eventually it will come back on by itself.
    Kudos to openSUSE and/or Linux for fixing something that always bothered me.  While all of the tmpfs mount points still seem to default to "half of RAM" for their size, free memory reported in LEAP 15.0 is very low.  I can be using my computer and only be using 1GB of my 8GB of RAM.

Compiling a Linux Kernel on OpenSUSE LEAP 15.0

    NOTE: this section is carried over from LEAP 42.3, but I have not yet gotten a kernel to compile properly:
    Some people have asked me how I got a kernel to compile on OpenSUSE LEAP 42.3.  I would like to go over this part in depth.  But first, a warning: if you are using AppArmor, and need what it offers, you should not proceed.  In my experience, compiling a new Linux kernel breaks AppArmor.  Also, I am not including instructions on how to make this work with UEFI/Secure Boot.  There are tutorials out there for that, and in my experience, Secure Boot is only a nuissance (see above).
    This "How To" assumes you are a home laptop or home desktop user and you are compiling a kernel specifically for the computer you are using OpenSUSE on.
    Now, some obligatory safety warnings.  First, before you begin, always back up your files.  I am not responsible for the loss of your files.  Second, there is the rare possibility that compiling a kernel could break your installation of OpenSUSE or corrupt the data in your files.  It's rare, but it could happen.  I am not responsible for the loss of damage to anything.  Third, choosing to compile a custom kernel obligates you to follow Linux kernel security newsletters and otherwise keep yourself informed as to the status of the Linux kernel.  It also means you are more or less taking your Linux kernel out of the protective care of OpenSUSE's security team and handling your own security, at least for the Linux kernel.  Proceed at your own risk.
    First, you need to download the latest stable Linux kernel.
    Second, copy it to an area where you have plenty of space to compile it.  I have a 20GB root partition and I didn't have enough space: I had to move it to another place.
    Third, install patterns-openSUSE-devel_kernel.  It will install all the necessary packages to compile a kernel.  But keep in mind, it will auto-select the old kernel source: you can safely not install that specific package.  With the newest kernels, you also need to install libelf-devel because some newer ELF options in the kernel config have been added.
    Fourth, as root, go unpack the kernel source (example, tar -xf linux-4.14.1.tar.xz).
    Fifth, configure the kernel.  If you do not know how, my advice is to start with the OpenSUSE configuration and then tailor it to your computer.  This means you need to know what hardware you have (the lspci command can help you).  One way to make this simple is use the "oldconfig" feature, which means the kernel will prompt you about new items.  This feature usually presents you with a yes/no/module type of decision per item, but makes the recommended choice the default, meaning you could just keep pressing enter.  So an easy way to do this is (assuming you are presently in the kernel source directory):

cp /boot/config-4.4.92-31-default .config
yes "" | make oldconfig

    Now, let's go into the kernel configuration tool using the command make menuconfig.
    The first thing you should do is, under general setup, change the local version to "-custom" or something that's different from OpenSUSE's "default" naming convention.
    Second, we will need to save space.  I recommend making the following changes:

    This should reduce the size of your Linux kernel dramatically.

    Now some things that can improve the response of your kernel and therefore your whole system:

    Next, a few general recommendations.  If you have a laptop, like I do, you know that there are several things that will never happen, such as replacing the PCIE sound card or video card.  They're almost always permanently built into the motherboard of a laptop.  You can therefore not compile other PCIE sound and video card support.
    The best way to do this, if you are unsure, is look at the output of lspci and look at the companies who made your hardware.  If you read the options under Device Drivers > Sound cards, etc, you will see that there is a section for PCI sound cards.  So for me, since Intel made my sound, I turned off all sound cards listed in PCI that were not made by Intel.  Then I went into graphics support and basically did the same thing.  But read the options and know what the options are, and use Google if you need to.  DisplayPort, for example, isn't a company, it's a technology, and you want that because your USB-C port should support this.  You can use this "manufacturer" philosophy in other sections, too, but make sure that what you're enabling or disabling, or adding/removing as modules, isn't something you need.  Choosing the best kernel configuration for your computer is sort of like an art, and takes practice and experience, so don't be discouraged if you forget something important.  Just boot into a stock kernel and try the whole thing again.
    If you're new, basically don't change anything unless you're absolutely sure you should.  Read the help associated with the kernel items listed.  Most will say "if you're unsure...", which can help, but I find that Googling the hardware item in question also helps.  Another helpful thing to do can be to go into Windows's Device Mangler ... I mean Manager (LOL) ... and writing down everything listed.  If you know, for instance, that you do not have a PCMCIA card (like this laptop), you can safely comment all those out under Bus types, etc.  But keep in mind that even some new laptops like this have legacy items like the ISA bus. (Why this laptop has ISA bus items, I don't know, but it's listed in lspci, so I keep it in my kernel config.)
    Note that you should make everything in the cryptographic portions a module: if you get errors at boot with LUKS that it can't unlock your LUKS because of a failed dependency, that's because (in my experience) it expects CRC32 and others to be configured as modules.
    When we're done configuring our kernel, we compile it.  If you looked in /proc/cpuinfo, you know how many CPUs you have.  Add one to that number and then compile using the -j option with that number.  For this laptop, since I have two cores with Hyperthreading (i.e. 4 virtual core) that means I ran make -j5 bzImage && make -j5 modules && make -j5 modules_install.
    Once this is done, you need to copy some stuff.  There are three files you need to copy.  Here's how it went on my computer, as an example.

cp arch/x86_64/boot/bzImage /boot/vmlinuz-4.14.1-custom
cp .config /boot/config-4.14.1-custom
cp System.map /boot/System.map-4.14.1-custom

    Then you need to make an initrd.  I ran dracut /boot/initrd-4.14.1-custom 4.14.1-custom to build my initrd.
    Last, you need to update the boot loader.  In OpenSUSE, go into Yast2 and open the boot loader configuration program.  I simply unchecked, then rechecked the "use graphical console" and clicked Ok.  Basically, I made no changes, just made the program think I did, so it would update GRUB2.  Or, as root, simply run the "update-bootloader" command as root.  Some have said that this isn't necessary (as I may have this habit left over from LILO and my Slackware Linux days), but I still run it.
    Keep in mind, again, if you're using Secure Boot, you need to also sign that kernel image, which is an involved process.
    When you reboot, select "advanced options" or whatever it's called, and then look at the kernel versions.  You should see your new kernel.  If not, boot the old kernel and troubleshoot the problem.
    This is my current kernel compile philosophy for this laptop:

    Good luck!