Aalto Talk with Linus Torvalds

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Buffalo WZR-1750DHP + OpenWRT

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This is the first of a series of posts about Linux kernel development for ARM. There will be one or two more posts before we get into the Kernel, describing tasks as building, and configuring OpenWRT. Maybe I'll also write about de-bricking devices if I manage to do something silly with my router. :-) What I like about the Buffalo WZR-1750DHP are the specs and the case without external antennas. It has a dual core ARM CPU with 512MB of RAM, and two wifi adapters: One for 2.4GHz and other for 5GHz. I was expecting that to install OpenWRT in a device like the WZR-1750DHP, it would require to find and use a serial port. Luckily that's not necessary. All the procedure was done over friendly web interfaces. As the router do not allow to install random firmware images, there are some workarounds to install OpenWRT. The steps I used are: 1 - Install and upgrade DD-WRT Download the latest versions of the files  factory-to-dd-wrt.bin and  buffalo-wzr...
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How to tell rpmbuild the number of simultaneous jobs? (make -j)

On Fedora 15, setting the environment variable RPM_BUILD_NCPUS allows you to configure the number up to 16 simultaneous jobs. For example to set the number of simultaneous jobs to 12, so rpmbuild will call make -j12: $ export RPM_BUILD_NCPUS=12 But if you need more than 16 simultaneous jobs, you will need to edit ~/.rpmmacros file. To allow numbers greater than 16, I've modified this file to: [peter@notepeter ~]$ cat .rpmmacros %_topdir %(echo $HOME)/rpmbuild %_smp_mflags %( \ [ -z "$RPM_BUILD_NCPUS" ] \\\ && RPM_BUILD_NCPUS="`/usr/bin/getconf _NPROCESSORS_ONLN`"; \\\ if [ "$RPM_BUILD_NCPUS" -gt 16 ]; then \\\ echo "-j $RPM_BUILD_NCPUS "; \\\ elif [ "$RPM_BUILD_NCPUS" -gt 3 ]; then \\\ echo "-j$RPM_BUILD_NCPUS"; \\\ else \\\ echo "-j3"; \\\ fi ) %__arch_install_post \ [ "%{buildarch}" = "noarch" ] || QA_CHECK_RPATHS=1 ; \ case "${QA_CHECK_RPATHS:-}" in ...
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Adding a serial console to the Buffalo Air Station WZR-1750DHP

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Playing with custom kernels and OpenWRT... It took me more than a month to flash a kernel that won't boot, but I did it yesterday. So the only way was to open the case, and connect the cables to access the serial console. Here is what I learned. Before you start Tools For opening the case you will need to remove two screws that are similar to those of mobile phones. I don't know the type name nor the size, so I recommend you to check type and size before starting. The screws are under the adhesive on the back of the router near the power plug and the mode button. UPDATE: Matt Sealey posted a comment saying that the screws are Torx T6. Thank you Matt! USB to Serial You will need something to connect your computer to the serial interface of the router. The most common solution is to use an USB to serial adapter. There are plenty of options, but I'm using this one that I bought on Ebay for less than € 10. Search for 'FT232RL' on your favorite online store....
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