Re: Memory detection problem in 2.4.19-rc2

[Leonardo Gomes Figueira <sabbath@planetarium.com.br>]

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Adrian Bunk wrote:

> It seems that the change Christoph introduced (from Red Hat's tree) in the
> lines around 810 (line number in -rc3) in arch/i386/kernel/setup.c didn't
> consider the case that someone want's to _in_crease the size of the memory
> by using the "mem="  parameter.
> 
> It's the following Changeset:
> 
> <--  snip  -->
> 
>    Changeset details for 1.383.2.25
> 
>    ChangeSet@1.383.2.25  2002-04-15 23:18:40-03:00  hch@infradead.org
>    all diffs
>    [PATCH] mem= command lines fixes.
>    Another patch from Red Hat's tree:
>      mem= command-line adapts itself to existing e820 values.
>      without this patch mem=xxxM ignores bios-reserved areas and uses
>      them as RAM. This patch makes the kernel skip these areas
>    arch/i386/kernel/setup.c@1.38  2001-04-05
>    21:19:09-03:00  hch@infradead.org
> 
> <--  snip  -->

Thanks for your help. I changed the code to the way it was before and it 
worked fine. I'm running 2.4.19-rc3 now. :-)

I created a patch to undo this modification in case anyone has the same 
problem, it's attached in this message.

Bye,

   Léo


  Leonardo Gomes Figueira
  sabbath@planetarium.com.br

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--- linux/arch/i386/kernel/setup.c.original	Mon Jul 22 21:44:45 2002
+++ linux/arch/i386/kernel/setup.c	Tue Jul 23 03:38:08 2002
@@ -808,21 +808,29 @@
 				userdef = 1;
 			} else {
 				/* If the user specifies memory size, we
-				 * limit the BIOS-provided memory map to
-				 * that size. exactmap can be used to specify
-				 * the exact map. mem=number can be used to
-				 * trim the existing memory map.
+				 * blow away any automatically generated
+				 * size
 				 */
 				unsigned long long start_at, mem_size;
  
+				if (userdef == 0) {
+					/* first time in: zap the whitelist
+					 * and reinitialize it with the
+					 * standard low-memory region.
+					 */
+					e820.nr_map = 0;
+					userdef = 1;
+					add_memory_region(0, LOWMEMSIZE(), E820_RAM);
+				}
 				mem_size = memparse(from+4, &from);
-				if (*from == '@') {
+				if (*from == '@')
 					start_at = memparse(from+1, &from);
-					add_memory_region(start_at, mem_size, E820_RAM);
-				} else {
-					limit_regions(mem_size);
+				else {
+					start_at = HIGH_MEMORY;
+					mem_size -= HIGH_MEMORY;
 					userdef=1;
 				}
+				add_memory_region(start_at, mem_size, E820_RAM);
 			}
 		}