README revision 1.5.6.2
1 1.5.6.2 yamt $NetBSD: README,v 1.5.6.2 2006/06/21 14:50:54 yamt Exp $ 2 1.5.6.2 yamt 3 1.5.6.2 yamt NetBSD for the Linksys NSLU2 (a.k.a. "Slug") 4 1.5.6.2 yamt ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 5 1.5.6.2 yamt 6 1.5.6.2 yamt The NSLU2 (Network Storage Link for USB 2.0 Disk Drives) is a small, cheap 7 1.5.6.2 yamt NAS device consisting of an Intel IXP420 (Xscale) CPU, a 10/100mbit Ethernet 8 1.5.6.2 yamt port, and two USB 2.0 ports. It has 32MB of SDRAM and 8MB of Flash memory, 9 1.5.6.2 yamt and runs RedBoot/Linux out of the box. 10 1.5.6.2 yamt 11 1.5.6.2 yamt It is eminently hackable. 12 1.5.6.2 yamt 13 1.5.6.2 yamt The guys over at http://www.nslu2-linux.org/ have done a good job of 14 1.5.6.2 yamt documenting just about every aspect of the hardware and original firmware. 15 1.5.6.2 yamt They also provide a custom "Unslung" Linux distribution to replace the 16 1.5.6.2 yamt original hobbled kernel/userland. 17 1.5.6.2 yamt 18 1.5.6.2 yamt Because of the amount of documentation available, and the fact that Slugs 19 1.5.6.2 yamt are available so cheaply (I paid just over UKP 50 for mine, brand new) I 20 1.5.6.2 yamt decided to buy one and port NetBSD to it. 21 1.5.6.2 yamt 22 1.5.6.2 yamt This is the result of that effort. 23 1.5.6.2 yamt 24 1.5.6.2 yamt Note: The Slug's IXP420 CPU runs in big-endian mode, so when building a 25 1.5.6.2 yamt cross toolchain you must pass "-m evbarm -a armeb" to build.sh. 26 1.5.6.2 yamt 27 1.5.6.2 yamt 28 1.5.6.2 yamt 29 1.5.6.2 yamt Current status 30 1.5.6.2 yamt ============== 31 1.5.6.2 yamt 32 1.5.6.2 yamt The following bits of Slug hardware are not (yet?) supported: 33 1.5.6.2 yamt 34 1.5.6.2 yamt - NPE Ethernet 35 1.5.6.2 yamt Someone will have to port Intel's IXP425 access library before this can 36 1.5.6.2 yamt be made to work. If that someone is you, the source code is available 37 1.5.6.2 yamt online here: 38 1.5.6.2 yamt 39 1.5.6.2 yamt http://www.intel.com/design/network/products/npfamily/ixp425.htm 40 1.5.6.2 yamt 41 1.5.6.2 yamt Look under "Tools & Software", then select "Intel(R) IPXX400 Software" 42 1.5.6.2 yamt to downlod the documentation. If you aren't registered, select 43 1.5.6.2 yamt "Register/Login" first. Documentation is available in the 44 1.5.6.2 yamt "Technical Documents" section. 45 1.5.6.2 yamt 46 1.5.6.2 yamt The easiest option will be to download the non-crypto version of the 47 1.5.6.2 yamt Access Library. The crypto-enabled version requires a lot more form 48 1.5.6.2 yamt filling. The Slug's IXP420 has no crypto capabilities anyway. 49 1.5.6.2 yamt 50 1.5.6.2 yamt - Flash ROM 51 1.5.6.2 yamt You can write gzboot kernels (when support is added) to Flash using 52 1.5.6.2 yamt RedBoot, so all is not lost. 53 1.5.6.2 yamt 54 1.5.6.2 yamt - Buzzer 55 1.5.6.2 yamt In the absence of a decent API to expose the onboard buzzer to userland, 56 1.5.6.2 yamt this is not yet supported. I envisage using timer1 to generate an 57 1.5.6.2 yamt interrupt at the required rate (1-2 kHz). The handler will toggle the 58 1.5.6.2 yamt buzzer GPIO pin. Obviously timer1 will be configured only when necessary 59 1.5.6.2 yamt as a 1-2 kHz interrupt rate will sap a fair bit of CPU horsepower. 60 1.5.6.2 yamt 61 1.5.6.2 yamt Everything else is fully supported, including the power/reset buttons and 62 1.5.6.2 yamt disk activity/status LEDs. 63 1.5.6.2 yamt 64 1.5.6.2 yamt Non-hardware items on the TODO list include: 65 1.5.6.2 yamt 66 1.5.6.2 yamt - gzboot support. 67 1.5.6.2 yamt The Slug's 8MB of Flash is split into 5 segments: 68 1.5.6.2 yamt 69 1.5.6.2 yamt 1 0x50000000-0x5003ffff: RedBoot (with some additional bits at the end). 70 1.5.6.2 yamt 2 0x50040000-0x5005ffff: Sysconf (used by the Linksys firmware). 71 1.5.6.2 yamt 3 0x50060000-0x5015ffff: Self-extracting compressed kernel image. 72 1.5.6.2 yamt 4 0x50160000-0x507dffff: Compressed ramdisk image. 73 1.5.6.2 yamt 5 0x507e0000-0x507fffff: SerComm Flash trailer. 74 1.5.6.2 yamt 75 1.5.6.2 yamt Segments 1, 2, and 5 should be considered immutable. Segments 3 and 4 76 1.5.6.2 yamt have a 16-byte header, the first 4 bytes of which describe the length 77 1.5.6.2 yamt of the image contained in that segment (not including the header). 78 1.5.6.2 yamt 79 1.5.6.2 yamt On power-up, RedBoot copies the image in segment 3 into SDRAM at 0x01d00000, 80 1.5.6.2 yamt and the image in segment 4 into SDRAM at 0x01000000. RedBoot then jumps to 81 1.5.6.2 yamt 0x01d00000. This is just a regular ARM Linux compressed kernel bootloader. 82 1.5.6.2 yamt 83 1.5.6.2 yamt So, we need to create a version of gzboot linked not at Flash address 84 1.5.6.2 yamt 0x50060000, but at 0x01d00000 instead. The only downside is that it looks 85 1.5.6.2 yamt like the combined size of gzboot plus compressed kernel cannot exceed 1MB. 86 1.5.6.2 yamt 87 1.5.6.2 yamt To support an md(4) root filesystem, we will need to modify gzboot to 88 1.5.6.2 yamt decompress the ramdisk image from segment 4 and copy it to the correct 89 1.5.6.2 yamt place in the decompressed kernel image. 90 1.5.6.2 yamt 91 1.5.6.2 yamt - Move the kernel link address closer to the start of SDRAM. We waste a 92 1.5.6.2 yamt little under 2MB with the current setup. 93 1.5.6.2 yamt 94 1.5.6.2 yamt 95 1.5.6.2 yamt 96 1.5.6.2 yamt Getting NetBSD onto the NSLU2 97 1.5.6.2 yamt ============================= 98 1.5.6.2 yamt 99 1.5.6.2 yamt Thanks to the efforts of the guys over at www.nslu2-linux.org, hacking the 100 1.5.6.2 yamt Slug is a pretty easy proposition, but some soldering skills are essential. 101 1.5.6.2 yamt For a first-time install of NetBSD (at least until someone comes up with a 102 1.5.6.2 yamt nice easy binary install image) you will almost certainly require access to 103 1.5.6.2 yamt the serial console. This means firing up your trusty soldering iron and 104 1.5.6.2 yamt hooking up a MAX3232 chip to your Slug. While your soldering iron is hot, 105 1.5.6.2 yamt you should seriously consider de-restricting your Slug's CPU core clock 106 1.5.6.2 yamt speed (133MHz stock, 266MHz de-restricted) by removing a single surface- 107 1.5.6.2 yamt mount resistor. Full instructions for both the these mods are on the above 108 1.5.6.2 yamt website. 109 1.5.6.2 yamt 110 1.5.6.2 yamt Once you have console access you can interrupt RedBoot's auto-boot process 111 1.5.6.2 yamt using CTRL-C. You are now in a position to download a NetBSD kernel into 112 1.5.6.2 yamt SDRAM. 113 1.5.6.2 yamt 114 1.5.6.2 yamt You will have to configure a TFTP server on a machine hooked up to the same 115 1.5.6.2 yamt Ethernet segment as the Slug. This machine's Ethernet interface must also 116 1.5.6.2 yamt be configured to have an address in the 192.168.0.0/24 subnet since the 117 1.5.6.2 yamt Slug's Ethernet *always* defaults to 192.168.0.1 when running RedBoot. 118 1.5.6.2 yamt There seems to be no way to alter this, so the best course of action will 119 1.5.6.2 yamt probably be to set up an alias on the server's interface. 192.168.0.2 is 120 1.5.6.2 yamt a good choice. 121 1.5.6.2 yamt 122 1.5.6.2 yamt Assuming you've done all that and have dropped a suitable kernel image 123 1.5.6.2 yamt into the TFTP directory, the following commands will load and run the 124 1.5.6.2 yamt kernel. 125 1.5.6.2 yamt 126 1.5.6.2 yamt redboot> ip_address -h 192.168.0.2 127 1.5.6.2 yamt redboot> load -r -b 0x200000 netbsd.bin 128 1.5.6.2 yamt redboot> go 129 1.5.6.2 yamt 130 1.5.6.2 yamt At this point your only real option is to mount the root filesystem from 131 1.5.6.2 yamt a USB disk device as the onboard Ethernet is not (yet?) supported. However, 132 1.5.6.2 yamt there's nothing to stop you using a USB-Ethernet interface... 133 1.5.6.2 yamt 134 1.5.6.2 yamt Note that the kernel will always report the CPU core clock speed as 266MHz 135 1.5.6.2 yamt even if your Slug's CPU clock is running at a stock 133MHz. 136 1.5.6.2 yamt 137 1.5.6.2 yamt 138 1.5.6.2 yamt 139 1.5.6.2 yamt Burning a NetBSD kernel into Flash 140 1.5.6.2 yamt ================================== 141 1.5.6.2 yamt 142 1.5.6.2 yamt TBD (waiting for gzboot support). 143 1.5.6.2 yamt 144
Indexes created Sun Nov 02 07:10:05 GMT 2025