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by jens.maus
Mon Jun 08, 2020 12:14 pm
Forum: Ubuntu
Topic: Ubuntu from SSD - easy method
Replies: 16
Views: 4153

Re: Ubuntu from SSD - easy method

Unfortunately there's still one missing bit: u-boot itself, despite having USB support compiled in (and despite apparently having USB mass-storage compiled in) ... doesn't see any mass storage devices whenever I've tested it! I've not yet had time to dig into this (beyond examining the compile time...
by jens.maus
Sat Jun 06, 2020 9:27 pm
Forum: Troubleshooting
Topic: u-boot port on RaspberryPi 4
Replies: 23
Views: 6106

Re: u-boot port on RaspberryPi 4

@agherzan Excellent job, agherzan! Can't wait to test this on my lab RPi4 and eventually seeing it upstreamed! I'm primarily interested in using U-Boot to netboot a kernel/initrd via Ethernet, with just U-Boot and the firmware blobs residing on the SD card, this already works beautifully on RPi2/3. ...
by jens.maus
Sun Jul 07, 2019 8:30 am
Forum: Troubleshooting
Topic: u-boot port on RaspberryPi 4
Replies: 23
Views: 6106

Re: u-boot port on RaspberryPi 4

Hi. I'm currently stuck a little and I think I will be needing a hardware debugger from here on. Currently I have logs on the serial but uboot hangs as soon as MMU is enabled (again this is only in 64bit, I haven't tried it on 32). I pushed a branch in github (https://github.com/agherzan/u-boot/tre...
by jens.maus
Sat Jul 06, 2019 9:02 pm
Forum: Troubleshooting
Topic: u-boot port on RaspberryPi 4
Replies: 23
Views: 6106

Re: u-boot port on RaspberryPi 4

Sorry, but I just stumbled over your post here and I actually wonder if you have any working u-boot version at hand now that actually boots correctly with a raspberrypi4? Could you please share some information with us or point us at the right position where we could find a u-boot version for the ra...
by jens.maus
Thu Jun 21, 2018 12:33 pm
Forum: Advanced users
Topic: How to get udev ignoring GPIO states upon bootup?
Replies: 7
Views: 993

Re: How to get udev ignoring GPIO states upon bootup?

Sorry, but I was of course using the wiringPi numbering für GPIOs (see wiringPi for more info on the unified numbering there). I was of course referencing to gpio16=pin36, gpio20=pin38 and gpio21=pin40. So this is not the issue. The issue is really that udev is resetting IN/OUT modes of gpios once i...
by jens.maus
Thu Jun 21, 2018 7:33 am
Forum: Advanced users
Topic: How to get udev ignoring GPIO states upon bootup?
Replies: 7
Views: 993

Re: How to get udev ignoring GPIO states upon bootup?

Just to illustrate the issue once more: Here is the wiringpi output before udev started: | 36 | 0 | OUT | GPIO.27 | 27 | 16 | | 38 | 0 | OUT | GPIO.28 | 28 | 20 | | 40 | 0 | OUT | GPIO.29 | 29 | 21 | And here it is after udev was started: | 36 | 0 | OUT | GPIO.27 | 27 | 16 | | 38 | 0 | ALT0 | GPIO.2...
by jens.maus
Wed Jun 20, 2018 9:35 pm
Forum: Advanced users
Topic: How to get udev ignoring GPIO states upon bootup?
Replies: 7
Views: 993

Re: How to get udev ignoring GPIO states upon bootup?

Thanks for your reply and your suggestion. I, of course, know about the new 'gpio' command and this would indeed be a potential possibility to set a certain gpio to out right at the boot loader level. However, what I am searching for is a possibility that when starting udev it does not reset all gpi...
by jens.maus
Wed Jun 20, 2018 12:49 pm
Forum: Advanced users
Topic: How to get udev ignoring GPIO states upon bootup?
Replies: 7
Views: 993

How to get udev ignoring GPIO states upon bootup?

Hello RaspberryPiers, I am maintaining a project here where I use buildroot to be run on the RaspberryPi platform. During bootup udev is started to identify various devices, etc. I noticed that as soon as udev is started the first time (during bootup) it seems to resets all GPIO states (in/out) to t...
by jens.maus
Mon Jun 12, 2017 9:28 pm
Forum: Advanced users
Topic: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildroot)
Replies: 11
Views: 6440

Re: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildr

Just want to let everyone know that I found a solution for my problem. With the help of the buildroot community I was able to develop a solution where I could use a PARTUUID specifier to make sure my image is either booted from a SD card or from an external USB memory stick or hard disk. The solutio...
by jens.maus
Thu Jun 08, 2017 8:44 am
Forum: Advanced users
Topic: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildroot)
Replies: 11
Views: 6440

Re: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildr

edit3: Booting with root=LABEL= is also possible, but only with an initramfs after patching. Thanks for all the hints. However, my initial question remains open: How can I generate an appropriate initrd file from within a buildroot environment or from my x86-based cross compilation linux system whi...
by jens.maus
Wed Jun 07, 2017 2:36 pm
Forum: Advanced users
Topic: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildroot)
Replies: 11
Views: 6440

Re: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildr

Thanks for the replies and the comments about PARTUUID and UUID. The reason why I want to have LABEL= working is that in my build environment I just generate partitions with labels so that my distribution is independent on the UUID/PARTUUID changing with regenerating the filesystem. In the end the u...
by jens.maus
Fri Jun 02, 2017 9:22 am
Forum: Advanced users
Topic: Booting rootfs via "root=LABEL=" or "root=UUID=" (buildroot)
Replies: 11
Views: 6440

Booting rootfs via "root=LABEL=" or "root=UUID=" (buildroot)

Hi, I am currently fighting with getting my buildroot-generated project running in a way that it actually boots the root filesystem using "LABEL=" or "UUID=" specified on the kernel command-line. The reason for thisis, of course, that I want to deliver my image in a way that the cmdline.txt doesn't ...
by jens.maus
Sat Mar 18, 2017 7:37 pm
Forum: Advanced users
Topic: Prevent udev from loading amba-pl011 kernel module
Replies: 1
Views: 494

Re: Prevent udev from loading amba-pl011 kernel module

Does anyone in here know how I can prevent udev from actually loading any kernel module related to the UART resources of the RaspberryPi2/Pi3? I really don't know how I can prevent udev from taking care of this device because I want to actually take care of which module should be loaded myself (dur...
by jens.maus
Sat Mar 18, 2017 4:55 pm
Forum: Advanced users
Topic: Prevent udev from loading amba-pl011 kernel module
Replies: 1
Views: 494

Prevent udev from loading amba-pl011 kernel module

Hello RPi developers, I am writing here in the hope to get an answer for a udev related question regarding the AMBA PL011 serial driver because I am currently facing a problem where I need to ensure that this kernel driver is not automatically loaded. My current situation is as follows: I am working...
by jens.maus
Sun Jan 08, 2017 10:26 am
Forum: Advanced users
Topic: Freezing with RT-patch (Pi 3)
Replies: 24
Views: 9450

Re: Freezing with RT-patch (Pi 3)

Hi again, now that the freezing seems to be solved with the patch mentioned above I just recognised that I am receiving the following dmesg notifications from time to time: [ 96.333042] NOHZ: local_softirq_pending 80 [ 108.953020] NOHZ: local_softirq_pending 80 [ 2251.054859] NOHZ: local_softirq_pen...
by jens.maus
Sat Jan 07, 2017 12:37 pm
Forum: Advanced users
Topic: Freezing with RT-patch (Pi 3)
Replies: 24
Views: 9450

Re: Freezing with RT-patch (Pi 3)

Yes, finally there is a fix, provided by the linux-rt kernel developers (actually by Ossama Gorbhel). You may find a description and a link to the patch at: https://www.osadl.org/Single-View.111+M5c03315dc57.0.html I have not yet tested it, but the test system at OSADL running a real-time cyclictes...
by jens.maus
Wed Jan 04, 2017 11:30 pm
Forum: Advanced users
Topic: Freezing with RT-patch (Pi 3)
Replies: 24
Views: 9450

Re: Freezing with RT-patch (Pi 3)

Hello, please note that I was suffering from the exact same symptoms as mentioned here. Here, I am using Linux kernel version 4.4.38 with the 4.4.38-rt49 PREEMPT_RT kernel patches under a buildroot 2016.11 driven system and my RaspberryPi3 was freezing after some time until the watchdog automaticall...
by jens.maus
Mon Jan 02, 2017 10:31 pm
Forum: Device Tree
Topic: Querying the UART clock rate from within a kernel module?
Replies: 5
Views: 2649

Re: Querying the UART clock rate from within a kernel module

* If you want your driver to work with a standard kernel image then the best route is probably to give your driver a different compatible string and use an overlay to select it (option b). The overlay will be really simple, and I'm happy to help with that. If you could provide that code to generate...
by jens.maus
Mon Jan 02, 2017 10:43 am
Forum: Device Tree
Topic: Querying the UART clock rate from within a kernel module?
Replies: 5
Views: 2649

Re: Querying the UART clock rate from within a kernel module

[...] However, the DT differences won't affect your driver code. The important properties for you are "compatible" and "clocks" - the "compatible" string(s) are there to allow the kernel to locate a driver for the device, while "clocks" declares an array of two clocks, "uartclk" and "apb_pclk". As ...
by jens.maus
Sun Jan 01, 2017 11:06 am
Forum: Device Tree
Topic: Querying the UART clock rate from within a kernel module?
Replies: 5
Views: 2649

Querying the UART clock rate from within a kernel module?

Hi, I am fairly new to the RaspberryPi firmware so please excuse if I am asking things that sound obvious to many of you. I still hope, however, that one of you guys could answer my questions in good time and with enough detail that I can use that for my projects. In a project using buildroot as the...

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