Real and availible RAM

[Kyle Rollin]

On Mon, 5 May 2003 09:30:30 -0400 (EDT), agent dero wrote
> I have been looking through the kernel boot messages in /var/log 
> while working on some custom kernel compile work, and I came across 
something
> that I think is very interesting, but doesn't make sense.
> real memory  = 100663296 (98304K bytes)
> avail memory = 94580736 (92364K bytes)
> 
> This tells me that FreeBSD recognizes my 98MB of RAM, but it only 
> uses 92MB? Are the 6MB of RAM that are left getting shafted, and 
> just using power, but not being addressed by FreeBSD? Does this slow 
> down my machine at all, I mean, is there a percentage to this? Where 
> only x% of 100% RAM is availible or usable?
> 

<snip> 

If you look at the way x86 architecture is designed (and somebody else can 
feel free to correct me if I'm wrong), but system memory is often used in 
the caching/shadowing of BIOS. This is where a lot of system memory often 
goes before the OS is loaded - also, as Rob said, the kernel itself will 
take up memory before the rest of the OS is booted. 

If you're concerned that you might run out of memory, RAM is cheap - adding 
a stick of 128MB will greatly reduce that risk :)

-Kyle Rollin