README revision 1.5.6.3
1 1.5.6.3 yamt $NetBSD: README,v 1.5.6.3 2007/02/26 09:06:20 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 - Flash ROM 35 1.5.6.2 yamt You can write gzboot kernels (when support is added) to Flash using 36 1.5.6.2 yamt RedBoot, so all is not lost. 37 1.5.6.2 yamt 38 1.5.6.2 yamt - Buzzer 39 1.5.6.2 yamt In the absence of a decent API to expose the onboard buzzer to userland, 40 1.5.6.2 yamt this is not yet supported. I envisage using timer1 to generate an 41 1.5.6.2 yamt interrupt at the required rate (1-2 kHz). The handler will toggle the 42 1.5.6.2 yamt buzzer GPIO pin. Obviously timer1 will be configured only when necessary 43 1.5.6.2 yamt as a 1-2 kHz interrupt rate will sap a fair bit of CPU horsepower. 44 1.5.6.2 yamt 45 1.5.6.2 yamt Everything else is fully supported, including the power/reset buttons and 46 1.5.6.2 yamt disk activity/status LEDs. 47 1.5.6.2 yamt 48 1.5.6.2 yamt Non-hardware items on the TODO list include: 49 1.5.6.2 yamt 50 1.5.6.2 yamt - gzboot support. 51 1.5.6.2 yamt The Slug's 8MB of Flash is split into 5 segments: 52 1.5.6.2 yamt 53 1.5.6.2 yamt 1 0x50000000-0x5003ffff: RedBoot (with some additional bits at the end). 54 1.5.6.2 yamt 2 0x50040000-0x5005ffff: Sysconf (used by the Linksys firmware). 55 1.5.6.2 yamt 3 0x50060000-0x5015ffff: Self-extracting compressed kernel image. 56 1.5.6.2 yamt 4 0x50160000-0x507dffff: Compressed ramdisk image. 57 1.5.6.2 yamt 5 0x507e0000-0x507fffff: SerComm Flash trailer. 58 1.5.6.2 yamt 59 1.5.6.2 yamt Segments 1, 2, and 5 should be considered immutable. Segments 3 and 4 60 1.5.6.2 yamt have a 16-byte header, the first 4 bytes of which describe the length 61 1.5.6.2 yamt of the image contained in that segment (not including the header). 62 1.5.6.2 yamt 63 1.5.6.2 yamt On power-up, RedBoot copies the image in segment 3 into SDRAM at 0x01d00000, 64 1.5.6.2 yamt and the image in segment 4 into SDRAM at 0x01000000. RedBoot then jumps to 65 1.5.6.2 yamt 0x01d00000. This is just a regular ARM Linux compressed kernel bootloader. 66 1.5.6.2 yamt 67 1.5.6.2 yamt So, we need to create a version of gzboot linked not at Flash address 68 1.5.6.2 yamt 0x50060000, but at 0x01d00000 instead. The only downside is that it looks 69 1.5.6.2 yamt like the combined size of gzboot plus compressed kernel cannot exceed 1MB. 70 1.5.6.2 yamt 71 1.5.6.2 yamt To support an md(4) root filesystem, we will need to modify gzboot to 72 1.5.6.2 yamt decompress the ramdisk image from segment 4 and copy it to the correct 73 1.5.6.2 yamt place in the decompressed kernel image. 74 1.5.6.2 yamt 75 1.5.6.2 yamt - Move the kernel link address closer to the start of SDRAM. We waste a 76 1.5.6.2 yamt little under 2MB with the current setup. 77 1.5.6.2 yamt 78 1.5.6.2 yamt 79 1.5.6.2 yamt 80 1.5.6.2 yamt Getting NetBSD onto the NSLU2 81 1.5.6.2 yamt ============================= 82 1.5.6.2 yamt 83 1.5.6.2 yamt Thanks to the efforts of the guys over at www.nslu2-linux.org, hacking the 84 1.5.6.2 yamt Slug is a pretty easy proposition, but some soldering skills are essential. 85 1.5.6.2 yamt For a first-time install of NetBSD (at least until someone comes up with a 86 1.5.6.2 yamt nice easy binary install image) you will almost certainly require access to 87 1.5.6.2 yamt the serial console. This means firing up your trusty soldering iron and 88 1.5.6.2 yamt hooking up a MAX3232 chip to your Slug. While your soldering iron is hot, 89 1.5.6.2 yamt you should seriously consider de-restricting your Slug's CPU core clock 90 1.5.6.2 yamt speed (133MHz stock, 266MHz de-restricted) by removing a single surface- 91 1.5.6.2 yamt mount resistor. Full instructions for both the these mods are on the above 92 1.5.6.2 yamt website. 93 1.5.6.2 yamt 94 1.5.6.2 yamt Once you have console access you can interrupt RedBoot's auto-boot process 95 1.5.6.2 yamt using CTRL-C. You are now in a position to download a NetBSD kernel into 96 1.5.6.2 yamt SDRAM. 97 1.5.6.2 yamt 98 1.5.6.2 yamt You will have to configure a TFTP server on a machine hooked up to the same 99 1.5.6.2 yamt Ethernet segment as the Slug. This machine's Ethernet interface must also 100 1.5.6.2 yamt be configured to have an address in the 192.168.0.0/24 subnet since the 101 1.5.6.2 yamt Slug's Ethernet *always* defaults to 192.168.0.1 when running RedBoot. 102 1.5.6.2 yamt There seems to be no way to alter this, so the best course of action will 103 1.5.6.2 yamt probably be to set up an alias on the server's interface. 192.168.0.2 is 104 1.5.6.2 yamt a good choice. 105 1.5.6.2 yamt 106 1.5.6.2 yamt Assuming you've done all that and have dropped a suitable kernel image 107 1.5.6.2 yamt into the TFTP directory, the following commands will load and run the 108 1.5.6.2 yamt kernel. 109 1.5.6.2 yamt 110 1.5.6.2 yamt redboot> ip_address -h 192.168.0.2 111 1.5.6.2 yamt redboot> load -r -b 0x200000 netbsd.bin 112 1.5.6.2 yamt redboot> go 113 1.5.6.2 yamt 114 1.5.6.3 yamt At this point you should mount a root filesystem from a USB disk device. 115 1.5.6.3 yamt The ethernet is now supported, so you may also be able to use a NFS root. 116 1.5.6.3 yamt USB Ethernet devices can also be used for a NFS root. 117 1.5.6.2 yamt 118 1.5.6.2 yamt Note that the kernel will always report the CPU core clock speed as 266MHz 119 1.5.6.2 yamt even if your Slug's CPU clock is running at a stock 133MHz. 120 1.5.6.2 yamt 121 1.5.6.2 yamt 122 1.5.6.2 yamt Burning a NetBSD kernel into Flash 123 1.5.6.2 yamt ================================== 124 1.5.6.2 yamt 125 1.5.6.2 yamt TBD (waiting for gzboot support). 126 1.5.6.2 yamt 127
Indexes created Sat Nov 01 05:10:12 GMT 2025