![]() ![]() The u-Boot bootloader, the bootloader’s environment/configuration space, the kernel and filesystem is all stored – naturally – on non-volatile flash. The GuruPlug’s memory consists of 512MB of NAND flash and 512MB of 800MHz DDR2 RAM. The bootloader should be accessible on the console port after power up. The bootloader installed on my Guruplug is u-Boot 2009.12-g28a9c08-dirty (– 18:15:21) and looks like a modified version by Marvell, the chip manufacturer of the 1.2GHz Kirkwood processor that powers the plug. The boot loader on the Guruplug is DAS u-Boot, or more commonly known as just u-Boot. OpenOCD, a free open source On Chip Debugger can then be used to program the device - essential if you break the bootloader and need to recover it. Basically, the device has two USB to serial converters – they use one for the 2.5V asynchronous serial based console port and the other one as the JTAG port using the MPSSE. The JTAG board is based on a FTDI FT2232D dual USB serial port with Multi-Protocol Synchronous Serial Engine (MPSSE). ![]() ![]() When I pre-ordered the Guruplug Server Plus, Global Scale threw in a Guru Plug JTAG board that connects directly to the the GuruPlug’s JTAG and console ports. Over the years I have learnt, many times the hard way, that you really need to understand the memory maps, MTD (Memory Technology Device) flash partitions, bootloader and recovery process prior to diving in head first and flashing the device with your newly built kernel. The enthusiasm to do anything with this device rapidly died. In addition, with marginally rated capacitors in the power supply and Australia being 240V and not 110V and there was a high instance of power supply failure. An engineer at sometime, somewhere, underestimated the heat they could dissipate in such a small package and when the two ethernet ports were both used at gigabit rates, the unit would spontaneously reset. I was one of the excited individuals (picture Christmas time) to order the Guruplug Server Plus prior to its release, only to find out it was really the GuruPlug Server Plug plus Heat Problems when it arrived. This was my first serious adventure into the depths of the Guruplug. According to the opensource DisplayLink driver was added to the mainline kernel in version 2.6.38, so rather than recompiling the driver as a module for 2.6.38, I made the decision in under 100 milliseconds to upgrade the kernel to the latest whiz bang 2.6 version – 2.6.39.4 at time of publication. The kernel on my Guruplug is version 2.6.32-00007-g56678ec originally installed when it shipped from Global Scale Technologies in May 2010. It’s essentially an USB to DVI Video interface and just the thing to add a video display to my Guruplug. I have recently acquired an IoGear external DVI Video Interface using Display Link technology. ![]()
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