Adapting Linux for ARM

cctalk-request at classiccmp.org wrote: Message: 6 Date: Sat, 30 Jun 2012 01:47:24 -0300 From: "Alexandre Souza - Listas" <pu1bzz.listas at gmail.com> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Adapting linux for other ARM devices. Was:Raspberry Pi and America, Message-ID: <08b401cd567b$8e3cd550$6600a8c0 at tababook> Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=original An interesting question that may fit on this list There are lots of old ARM devices around. One that is very common in Brazil is the "easybox" internet computer which is an ARM device with an ISA slot (for originally a modem and optionally a NE2000 network board), some peripherals, video output and remote keyboard. These can be had for (very) cheap. How hard is to port e.g.: Angstrom or something like that for a system like this? Maybe I hadn't expressed myself well. I want to UNDERSTAND how the port is done Well, depending on the exact flavor of ARM CPU, it could be easy or VERY, VERY hard. The problem is that the ARM CPUs may all have essentially the same instruction set, but the on-chip peripheral configuration can be quite different. Also, some chips had significant bugs that needed workarounds. The ARM architecture spans a wide range of performance and capability. The Beagle Board is an amazing system on a 75 mm square board, with USB, HDMI 256 M RAM, SD memory card and runs on less than 2 W power. You can run a full Linux Ubuntu system on it. I use them for net-attached devices that export TCP services or Glade GUIs to control little boards that stack with the Beagle. If you have an existing port for a related chip, or a board that uses the same ARM chip, it may not be that difficult. There will be a source code base and a development tools environment. You mostly customize the list of drivers to be included, possibly providing some parameters to select what peripherals are enabled and how to route them to the board. If you are starting with a generic source tree and a chip that has not has Linux ported to it (or the port has not been updated in years) then it can be QUITE messy. I built an updated kernel for the Beagle board ON the beagle board, it took about a day to compile the kernel. That's why they use toolkits to do it on a PC. Jon