Difference between revisions of "Boot-parameters"

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= Boot Parameters =

== How to boot from SCSI Hard drive ==

This issue is more related to SCSI raid on servers, and an indication that it is happening is the following message at boot time, just after grub is launched.

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Volume group "VolGroup00" not found

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The way to fix this issue is adding to the kernel the `scsi_mod.scan=sync` parameter.

== How to enable extra serial ports ==

By default, only 4 serial ports are present on linux, known as `/dev/ttyS[0-3]`, but it happens that some times is necessary to handle more ports in order to reach any other devices hooked on such ports.

Before tell the kernel how many port it should mount, it will be necessary to copy from BIOS the `port` and `IRQ` for the needed ports.

Then we need to ensure that new serial ports are being set properly on boot time, it could be done by adding the command following command to `/etc/rc.local` file:

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setserial /dev/ttySn irq N port 0xDDDD uart 16550A baud_base 115200

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Where:

* `ttySn` is the port to be set

* `N` is the IRQ number

* `0xDDDD` is the port in four digits format

Also the speed could be modified in order to accomplish the device requirements.

To add more ports add to the kernel the `8250.nr_uarts=N` parameter, where `N` is the total desired amount of ports available.

== How to enable graphic cart at boot time on AMD Geode ==

On AMD Geode LX based terminals, the graphic card doesn't works with the standard frame buffer driver, that means the parameters `xdriver=vesa vga=792` won't work, or maybe yes but soonest will turn blank the screen and stop to work.

To solve this issue on AMD Geode terminals add to the kernel the `lxfb.mode_option=1024x768` parameter. ''1024x768'' could be changed to match the size of current monitor.

== How to setup screen size on Grub bootloader ==

In order to display small fonts on terminal is necessary to set the vga value as kernel parameter to enable the frame buffer vga mode, the following table shows the possible values:

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Color depth | 640x480 800x600 1024x768 1280x1024

-----------------+-------------------------------------

256 (8bit)| 769 771 773 775

32000 (15bit)| 784 787 790 793

65000 (16bit)| 785 788 791 794

16.7 Mill.(24bit)| 786 789 792 795

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