GRUB vs. big RTEMS executables

Dave Poirier futur at
Thu Mar 8 23:46:12 UTC 2001

In-Reply-To: <3AA80CE8.C532DAEC at>; from eric.norum at on Thu,
+08, 2001 at 04:51:20PM -0600

On Thu, Mar 08, 2001 at 04:51:20PM -0600, Eric Norum wrote:
> Until now my only RTEMS targets have been the Motorola MC68360
> and MVME167.  Now I'm moving to the wonderful world of x86
> hardware.  I'm using the RTEMS pc386 BSP with GRUB to build a
> boot floppy.  I've been able to run the RTEMS hello and ticker
> tests with no problems, even when I put a compressed image on
> the floppy.  But when I try to boot a really big executable:
>    text          data     bss     dec     hex filename
> 1177613         57911  123360 1358884  14bc24 bin/RTEMS-pc386/example
> which has been stripped and compressed before placing on the
> floppy, I get the following message from GRUB stage2:
> Loading below 1MB is not supported.
> Howcome smaller programs work, but big ones don't?
> Am I running into some problem causes by the stupid 640k memory
> boundary on a PC?
> --
> Eric Norum                                 eric.norum at
> Department of Electrical Engineering       Phone: (306) 966-5394
> University of Saskatchewan                 FAX:   (306) 966-5407
> Saskatoon, Canada.

somebody correct me if I'm wrong, btw, hi all, but there is an
header generated that grub reads.  It's header in the header or
the config of grub, but you can specify the location where to
load the image.

Yes, if that location is below the 1MB address range, you will
run into the 640KB problem.  If you just change that value for
above 1MB, it will be able to work as long as you have enough

Dave Poirier (eks at          Assembly language: My blood,                     my life, my spirit.. :)

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