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4. Firmware command reference

In this section, the NeTTrom parameters will be explained in detail. It is meant more as a reference guide; for most people, the examples in the `Using the firmware' chapter should be sufficient. The parameters are grouped into several sections that are logically connected - the same way they are listed when the printenv command is used.

4.1 Eth0 configuration

Eth0 is the 10-base-T network interface on the back of the NetWinder. If the minikernel is to do any networking (such as fetching a kernel, or booting from an NFS server), then the interface must be assigned an IP address and netmask in this section. Either static addresses or dynamic (DHCP) can be used.

The first parameter, netconfig_eth0, determines how the interface is configured. The default setting of disk means that the interface is not configured (inactive). A setting of flash means that the address and netmask are specified in the eth0_ip parameter. A setting of dhcp indicates that DHCP is to be used to configure the interface.

...dhcp parameters should be described here...

The eth0_ip parameter contains the network address and netmask value for the eth0 interface. The two values should be separated by a slash, and the netmask should be expressed as a single number (IPv6 style). This field is ignored unless netconfig_eth0 is set to flash.

4.2 Eth1 configuration

Eth1 is the 10/100-base-T network interface. It has a set of parameters that function identically to those of the eth0 interface. Consult the previous section for a full description.

4.3 Routing configuration

These options allow the firmware to contact boot servers (TFTP and NFS) that are not on the same subnet as the NetWinder. Issue the command setenv route1 with no additional arguments for some examples of how to set it up. This feature has not been widely tested.

4.4 Initial ram disk configuration

The bootloader can load an initial ram disk out of the flash memory. One common use for this feature is to provide a `rescue' filesystem that can be used to restore the hard disk, without needing to set up an NFS server and a TFTP server.

The initrd parameter can be set to either inactive or flash. In the latter case, the bootloader searches the flash memory for a compressed ram disk and arranges for it to be booted as the root device.

The other initrd options are not implemented as of this writing.

4.5 Kernel configuration

This section determines how the NetWinder will fetch its kernel. The first parameter, kernconfig, determines which method will be used to fetch the kernel. It can be set to one of partition, fs, or tftp.

Normally, kernconfig is set to fs, which stands for `filesystem'. In this case, the values of the parameters kerndev and kernfile determine the device and name of the kernel file. The bootloader will look on the specified device and try to load and execute the specified filename. The file should be a valid linux kernel.

Prior to the 2.0 firmware series, the kernel was stored in raw form on a dedicated partition (ie. without a filesystem). Support for this `legacy' method is available by setting kernconfig to partition. In this case, the kernel is loaded directly from the device specified by kerndev. There is no filename. Obviously, the root device must be on a different device in this case. Most people won't want to use this option.

The third option is to fetch a kernel via TFTP from a server on the network. Setting kernconfig to tftp enables this option, which also requires that a network interface be configured (see the section above). The ip address of the TFTP server should be stored into the kerntftpserver parameter, and the filename (on the server) should be stored in kerntftpfile.

The multiple file name fields are provided to make it easy to switch between network and local booting. Once configured, only the kernconfig parameter needs to be changed.

4.6 Root device configuration

The rootconfig parameter specifies how the NetWinder will obtain its root filesystem. The possible values are either disk for local booting, and nfs for network booting.

When the rootconfig parameter is set to disk, then the boot device specified by the rootdev parameter will be used. Typically the root device would be /dev/hda1 or some other hard drive partition. However, any devices that were detected at boot-up may be legitimately specified. For example, a ZIP drive attached on the parallel port could be used as the boot device.

Network booting is enabled by setting rootconfig to the value nfs. The IP address and the export name for the NFS server should be specified in the rootpath parameter (a typical example would be

4.7 Miscellaneous configuration

The cmdappend parameter can be used to specify additional options to be passed to the kernel. The contents of this field will be appended to the kernel command line, without any checking done. One common use is to pass special arguments to the init process.

The passwd parameter can be used to password-protect the firmware settings, to prevent unauthorized haxors (or young children) from messing with your configuration settings.

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