[LinuxBIOS] Fun easy question. 512Kb or 256Kb

Richard Smith smithbone at gmail.com
Tue Feb 7 18:46:38 CET 2006

On 2/7/06, Adam Talbot <talbotx at comcast.net> wrote:

> So let me take the path of messing with Linuxbios code instead of
> messing with hardware access times that may or may not effect my system
> and will be almost impossible to tell.

Good choice. *grin*

> Ron stated:

Richard actually. But Ron has lots of good things to say as well.

> "Sending a byte out the serial port at 115200 is approx 80 times slower
> than a ISA bios fetch. So you will have the most dramatic speed up by
> nuking anything that writes to the serial port"
> So if I turn off any serial console, that is fixed?

Do you mean serial console in Linux kernel or the Linuxbios serial
diagnostic output?

Linuxbios serial output dosen't do much (if any) buffering so its at
the bottom.  Set you log level to 0 and you will go the fastest.

Linux kernel serial console does slow down the kernel boot but since
it does some buffering its not quite as slow.  To a point. Once you
fill up the console buffer it will block until room is ready as well. 
Just like linuxbios.

>  Does VGA bios have
> the same problem?

No the VGA device lives on the PCI (or AGP) bus so the IO is done at
PCI speed which is very fast.  Video writes in general are some what
slow.  So the less you do the faster you will go.

Richard A. Smith

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