Re: Digest Number 275
Posted by
Arne Chr.Jorgensen
on 1999-12-11 08:36:17 UTC
CAD_CAM_EDM_DRO@onelist.com wrote:
If you have 64Mb of ram, and you have the X, as 63, then you have set the maximum memory
that Linux will use, as 63, - i.e. there is 64-63= 1Mb of high memory that Linux will not use. If
you set it to 62, - then you have set aside 2Mb, etc.
This memory is used as shared memory space. The RT kernel will access this memory and fetch
any instructions and data, and Linux can access this memory with special instructions, but the
"normal" Linux processes will not touch it. So EMC writes data into this region, and when the
RT kernel is running, it will read from this, and vise versa. EMC will not use all of the 1Mb memory,
- so there is there is nothing to gain by setting this to a larger size. But instead of setting aside any
value less than 1Mb - you have to calculate this in Kilo bytes. ( I do this on a 486 )
Hope this may help, - you will probably hear from many on the list, - I just used this opportunity
to say hello to you all. I have just been too busy with other things to chat :)
//ARNE
> > Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the discussion of shop built systems in the above catagories.Hi Karl,
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>
> There is 1 message in this issue.
>
> Topics in today's digest:
>
> 1. little linux
> From: Karl Klemm <kklemm@...>
>
> _______________________________________________________________________________
> _______________________________________________________________________________
>
> Message: 1
> Date: Fri, 10 Dec 1999 12:45:20 -0500 (EST)
> From: Karl Klemm <kklemm@...>
> Subject: little linux
>
> after I do make modules_install for the rtlinux kernel, 2.0.36, and edit
> lilo.conf and reboot it just stops. The first machine this happened on
> was bad and spit out an error, so forget about that, but the second was
> ok, and it just stopped, no error or anything. I did read somewhere that
> when you edit the lilo.conf file, if you have a different amount of memory
> that 32MB that you should put in a line such as append="mem=Xm" where X is
> one less than the amount of memory. Now, in the instructions that I
> received, X=63. My questions is, is X reffering to the amount of physial
> memory, RAM, or the linux swap space, and also if the wrong amount was in
> there would the machine stop?
>
> Karl
>
> _______________________________________________________________________________
> _______________________________________________________________________________
If you have 64Mb of ram, and you have the X, as 63, then you have set the maximum memory
that Linux will use, as 63, - i.e. there is 64-63= 1Mb of high memory that Linux will not use. If
you set it to 62, - then you have set aside 2Mb, etc.
This memory is used as shared memory space. The RT kernel will access this memory and fetch
any instructions and data, and Linux can access this memory with special instructions, but the
"normal" Linux processes will not touch it. So EMC writes data into this region, and when the
RT kernel is running, it will read from this, and vise versa. EMC will not use all of the 1Mb memory,
- so there is there is nothing to gain by setting this to a larger size. But instead of setting aside any
value less than 1Mb - you have to calculate this in Kilo bytes. ( I do this on a 486 )
Hope this may help, - you will probably hear from many on the list, - I just used this opportunity
to say hello to you all. I have just been too busy with other things to chat :)
//ARNE