Unlike how I usually treat software tools I work with, my attitude towards U-boot is “if it works, never mind how and why”. Trying to understand the gory details of U-boot has never been very rewarding. Things work or break more or less randomly, depending on which git revision is checked out. Someone sent a [...]
Since the device tree is the new way to set up hardware devices on embedded platforms, I hoped that I could avoid the “platform” API for picking which driver is going to take control over what. But it looks like the /arch/arm disaster is here to stay for a while, so I need to at [...]
This is my short saga about my not necessarily intelligent actions for reading a DocBook paper. So I wanted to read some documentation from my Linux kernel sources. It happened to be in DocBook format. In the kernel source’s root, I tried $ make htmldocs or I could have gone $ make pdfdocs Or mandocs. [...]
What this blob is all about Running some home-cooked SDMA scripts on Freescale’s Linux 2.6.28 kernel on an i.MX25 processor, I’m puzzled by the fact, that cache flushing with dma_map_single(…, DMA_TO_DEVICE) doesn’t hurt, but nothing happens if the calls are removed. On the other hand, attempting to remove cache invalidation calls, as in dma_map_single(…, DMA_FROM_DEVICE) [...]
The problem In short: Running linux 3.8.0 on Altera’s Cyclone V SoC, NetworkManager doesn’t bring up the Ethernet port. It also makes false accusations such as Jan 1 00:00:17 localhost NetworkManager[1206]: <info> (eth0): driver ‘stmmaceth’ does not support carrier detection. and later on also says Jan 1 00:00:17 localhost NetworkManager[1206]: <warn> (eth0): couldn’t get carrier [...]
Trying to insmod a kernel module, which was just compiled against the true headers of the running kernel, I got: # insmod mymodule.ko insmod: error inserting ‘mymodule.ko’: -1 Invalid module format And this in /var/log/syslog: mymodule: version magic ’3.3.0-xxx SMP preempt mod_unload ARMv7 ‘ should be ’3.3.0-xxx+ SMP preempt mod_unload ARMv7 ‘ Really? Are you [...]
Having some trouble to figure out what I should write in my own hand-written DTS entry for my logic, I ended up reading the sources of the Linux kernel (version 3.3, which is the currently used for Zynq). The purpose is to hook up a device defined in the PL of a Zynq-7000 (FPGA-style logic [...]
Looking at my system log (kernel 2.6.35.4), this is a common thing: Apr 24 12:04:49 kernel: radeon 0000:01:00.0: ffff8802d0aa1a00 reserve failed for wait Apr 24 12:04:49 kernel: radeon 0000:01:00.0: ffff8802d0aa1a00 reserve failed for wait Apr 24 12:04:51 kernel: radeon 0000:01:00.0: ffff8802d0aa1a00 reserve failed for wait Apr 24 12:04:51 kernel: radeon 0000:01:00.0: ffff8802d0aa1a00 reserve failed for [...]
It may help investigating the interrupt descriptors. For a 2.6.38 kernel, putting this in a kernel module load supplies some information (includes, declarations and code mixed below. Organize properly in your own module) #include <linux/irq.h> #include <linux/interrupt.h> #include <asm/irq.h> int i; struct irq_desc *desc; for_each_irq_desc(i, desc) { if (!desc) continue; printk(KERN_INFO “%d: status=%08x, chip=%08x, handle_irq=%08x\n”, [...]
What we have here As one can guess from my notes about the i.MX51′s external bus and the oscilloscope shots I’ve published, I made myself a small dissection kit for watching the bus’ lines activity with a digital oscilloscope. This is a good time to mention, that the kit was done quickly and dirty, so [...]
