Re: tlug: memory size strangeness(?)

[Christopher Sekiya <wileyc@example.com>]

On Mon, 19 Jan 1998, David J Iannucci wrote:

> Thanks for the answer.  I know that I'm supposed to disable shadow RAM
> for Linux, but the BIOS setup menus on neither of these machines seems
> to offer this option. 

Yep.  I know of only a few BIOS revisions (late AMI 386's, early AMI 486)
that allow shadow region relocation.  By and large, you'll lose that bit.

I take it back: there was a patch in the 1.1.x days (i.e., about four
years ago) that would allow the kernel to use UMBs as userspace memory.
Never was rolled into the kernel proper, don't know the status of that
patch now.

> But....... I find it hard to believe that the free command subtracts
> memory used by the kernel from the number which is supposed to indicate
> (I thought) the _total_ amount of RAM recognized by Linux (i.e. not
> simply the amount of memory free for use at this time).  Is this really
> the case? 

Such is in fact the case.  free(1) will return the amount of memory
available for user space (as opposed to kernel space).  For example ... my
machine has 64Kb.  This is what I get:

inasa:~$ free
             total       used       free     shared    buffers     cached
Mem:         62712      36976      25736      35592       3076      11592
-/+ buffers/cache:      22308      40404
Swap:        34236          0      34236


... and the kernel boot message (albeit an old one, but it'll give you the
idea) says:

Dec 30 00:11:47 inasa kernel: Memory: 62904k/65536k available (1052k
kernel code, 392k reserved, 1156k data, 32k init) 

So there you have it.

--	Chris (wileyc@example.com)

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