Handbook:MIPS/Blocks/HWReqs/es

Revise también el documento Requerimientos Hardware MIPS

Notas de instalación
En muchas arquitecturas, el procesador ha evolucionado a través de varias generaciones, cada una se construye con los fundamentos de la anterior. La arquitectura MIPS no es ninguna excepción. Hay varias generaciones de CPUs que se cubren en la arquitectura MIPS. Para elegir el archivo comprimido con la imagen de arranque desde red correcta es necesario conocer de qué familia de CPU dispone el sistema. Estas familias están descritas como las arquitecturas de conjuntos de instrucciones (Instruction Set Architecture o ISA).

Igualmente, una cuestión importante es familiarizarse con el concepto de extremidad (endianness). La extremidad se refiere al forma en que la CPU lee las palabras de la memoria principal. Una palabra se puede leer como extremo mayor (big endian) en el que el byte más significativo se lee primero o extremo menor (little endian) en el que el byte menos significativo se lee primer. Las máquinas Intel x86 son normalmente de extremo menor, en cambio las máquinas Apple y Sparc son de extremo mayor. En MIPS se utilizan ambos. Para diferenciarlos, se añade el a la arquitectura para denotar extremo menor (little endian).

Para el lector que desee saber más sobre ISAs, se recomienda visitar los siguientes sitios web:


 * Sitio Web Linux/MIPS: MIPS ISA
 * Sitio Web Linux/MIPS: Extremidad (Endianness)
 * Sitio Web Linux/MIPS: Procesadores
 * Wikipedia: Conjunto de instrucciones

Vistazo rápido al arranque desde la red
En esta sección cubriermos las necesidades para arrancar de forma correcta una estación de trabajo Silicon Graphics o una appliance de un servidor Cobalt Server desde la red. Esto es solo una guía rápida, no está pensada para incidir en todas las partes. Para obtener más información se recomienda leer el artículo sobre nodos sin disco.

Dependiendo de la máquina, se necesita cierto hardware para arrancar desde la red e instalar Linux.


 * En general:
 * DHCP/BOAMD Alchemy series, 4kc, 4km, many others... Hay pocas revisiones en el servidor ISA.OTP MIPS32 (se recomienda ISC DHCPd)
 * Paciencia (y mucha)
 * Para las estaciones de trabajo Silicon Graphics:
 * Servidor TFTP server (se recomienda tftp-hpa)
 * Cuando se necesita utilizar la consola serie:
 * MiniDIN8 --> Cable serie RS-232 (únicamente necesario para sistemas IP22 y IP28 systems)
 * Cable de módem nulo (Null-modem)
 * Terminal compatible VT100 o ANSI que pueda trabajar a 9600 baudios
 * Para los servidores Cobalt (NO el Qube original):
 * Servidor NFS
 * Cable de módem nulo (Null-modem)
 * Terminal compatible VT100 o ANSI que pueda trabajar a 115200 baudios

Congigurar TFTP y DHCP
Tal y como se ha mencionado anteriormente, esto no es una guía completa, se trata de una configuración mínima que hará que las cosas funcionen. Utilícela cuando se realice una configuración desde cero o utilice las sugerencias para modificar una configuración existente para dar soporte al arranque por red.

Merece la pena comentar que no es necesario que los servidores utilizados estén corriendo Gentoo Linux, podrían correr FreeBSD o cualquier plataforma tipo Unix. Sin embargo, en esta guía se asume que se va a utilizar Gentoo Linux. Se se quiere, también se puede correr TFTP/NFS en una máquina distinta a la que corre el servidor DHCP.

Primer paso: Configurar DHCP. Para que el demonio DHCP ISC responda a las peticiones BOOTP (tal y como requiere la BOOTROM de SGI y Cobalt), en primer lugar se debe habilitar BOOTP dinámico en el rango de direcciones que se usa. A continuación configure una entrada para cada cliente con punteros a la imagen de inicio.

Una vez instalado, cree. A continuación se muestra una configuración mínima para empezar a trabajar.

Con esta configuración se pueden añadir cualquier número de clientes dentro de la cláusula de la subred. Más adelante en este guía se cubre esto.

Next step - Setting up TFTP server. It is recommended to use tftp-hpa as it is the only TFTP daemon known to work correctly. Proceed by installing it as shown below:

This will create to store the netboot images. Move this elsewhere if necessary. For the purposes of this guide, it is assumed that it is kept in the default location.

Downloading a netboot image
Depending on the system the installation is meant for, there are several possible images available for download. These are all labelled according to the system type and CPU they are compiled for. The machine types are as follows:

Also in the filename, r4k refers to R4000-series processors, r5k for R5000, rm5k for the RM5200 and r10k for R10000. The images are available on the Gentoo mirrors.

DHCP configuration for an SGI client
After downloading the file, place the decompressed image file in the directory. (Use bzip2 -d to decompress) Then edit the file and add the appropriate entry for the SGI client.

Kernel options
We're almost done, but there's a couple of little tweaks still to be done. Pull up a console with root privileges.

Disable "Path Maximum Transfer Unit", otherwise SGI Prom won't find the kernel:

Set the port range usable by the SGI PROM:

This should be sufficient to allow the Linux server to play nice with SGI's PROM.

Starting the daemons
At this point, start the daemons.

If nothing went wrong in that last step then everything is all set to power on the workstation and proceed with the guide. If the DHCP server isn't firing up for whatever reason, try running on the command line and see what it says - if all is well, it should just fork into the background, otherwise it will display 'exiting.' just below its complaint.

An easy way to verify if the tftp daemon is running is to type the following command and confirm the output:

Netbooting the SGI station
Okay, everything is set, DHCP is running as is TFTP. Now it is time to fire up the SGI machine. Power the unit on - when "Running power-on diagnostics" comes on the screen, either click "Stop For Maintenance" or press. A menu similar to the following will show up.

Type in to enter the command monitor. On the monitor, start the BootP process:

From this point, the machine should start downloading the image, then, roughly 20 seconds later, start booting Linux. If all is well, a busybox ash shell will be started as shown below and the installation of Gentoo Linux can continue.

Troubleshooting
If the machine is being stubborn and refusing to download its image, it can be one of two things:


 * 1) The instructions were not followed correctly, or
 * 2) It needs a little gentle persuasion (No, put that sledge hammer down!)

Here's a list of things to check:


 * dhcpd is giving the SGI Machine an IP Address. There should be some messages about a BOOTP request in the system logs. is also useful here.
 * Permissions are set properly in the tftp folder (typically - should be world readable)
 * Check system logs to see what the tftp server is reporting (errors perhaps)

If everything on the server is checked, and timeouts or other errors occur on the SGI machine, try typing this into the console.

Overview of the netboot procedure
Unlike the SGI machines, Cobalt servers use NFS to transfer their kernel for booting. Boot the machine by holding down the left & right arrow buttons whilst powering the unit on. The machine will then attempt to obtain an IP number via BOOTP, mount the directory from the server via NFS, then try to download and boot the file  (depending on the model) which it assumes to be a standard ELF binary.

Downloading a Cobalt netboot image
Inside http://distfiles.gentoo.org/experimental/mips/historical/netboot/cobalt/ the necessary boot images for getting a Cobalt up and running are made available. The files will have the name nfsroot-KERNEL-COLO-DATE-cobalt.tar - select the most recent one and unpack it to as shown below:

NFS server configuration
Since this machine uses NFS to download its image, it is necessary to export on the server. Install the package:

Once that is done, place the following in the file.

Now, once that is done, start the NFS server:

If the NFS server was already running at the time, tell it to take another look at its exports file using exportfs.

DHCP configuration for a Cobalt machine
Now, the DHCP side of things is relatively straightforward. Add the following to the file.

Starting daemons
Now start the daemons. Enter the following:

If nothing went wrong in that last step all should be set to power on the workstation and proceed with the guide. If the DHCP server isn't firing up for whatever reason, try running on the command line and see what it tells - if all is well, it should just fork into the background, otherwise it will show 'exiting.' just below its complaint.

Netbooting the Cobalt machine
Now it is time to fire up the Cobalt machine. Hook up the null modem cable, and set the serial terminal to use 115200 baud, 8 bits, no parity, 1 stop bit, VT100 emulation. Once that is done, hold down the left and right arrow buttons whilst powering the unit on.

The back panel should display "Net Booting", and some network activity should be visible, closely followed by CoLo kicking in. On the rear panel, scroll down the menu until the "Network (NFS)" option then press. Notice that the machine starts booting on the serial console.

A busybox ash shell will pop up as shown below, from which the Gentoo Linux installation can continue.

Troubleshooting
If the machine is being stubborn and refusing to download its image, it can be one of two things:


 * 1) the instructions have not been followed correctly, or
 * 2) it needs a little gentle persuasion. (No, put that sledge hammer down!)

Here's a list of things to check:


 * dhcpd is giving the Cobalt Machine an IP Address. Notice messages about a BOOTP request in the system logs. is also useful here.
 * Permissions are set properly in the folder (should be world readable).
 * Make sure the NFS server is running and exporting the directory. Check this using  on the server.