Boot parameters

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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.

Volume group "VolGroup00" not found

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

How to enable extra serial ports

There are some systems that might use the ttyS4 and/or ttyS5 known in other worlds as COM5 and COM6 respectively. By default these ports are detected under Linux.

To enable the extra serial ports go into the BIOS, find the serial ports and write down the following data:

  • IRQ
  • PORT

With this info, add the following line for COM5 and above to /etc/rc.d/rc.local, make sure to place them before the elo driver command lines.

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


  • n is the number of the COM minus 1 (ttyS4 = COM5)
  • N is the IRQ
  • DDDD is the port number in hexadecimal format with 4 digits (2d8 = 02d8)

Then, tell the kernel that will have 6 ports on system running. To have done this edit the /etc/grub.conf file and add at the end of the kernel line the variable 8250.nr_uarts=6. The entry looks like: ... title Bashlinux

   root (hd0,0)
   kernel /vmlinuz-2.6.18-92.el5 ro root=LABEL=/ rhgb vga=792 quiet 8250.nr_uarts=6
   initrd /initrd-2.6.18-92.el5.img

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:

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