[syslinux] Limiting memory used by syslinux

[H. Peter Anvin]

On 06/04/2012 08:42 AM, jochen.desmet at emc.com wrote:
> Chris Dion came up with the following patch which seems
> to do the trick for now:
> 
> --- syslinux-3.82.orig//com32/lib/malloc.c      2009-06-09 13:19:25.000000000 -0400
> +++ syslinux-3.82/com32/lib/malloc.c    2012-06-03 10:42:48.000000000 -0400
> @@ -34,7 +34,7 @@
>    return sp;
>  }
> 
> -#define E820_MEM_MAX 0xfff00000        /* 4 GB - 1 MB */
> +#define E820_MEM_MAX 0x40000000        /* 1GB */
> 
>  static int consider_memory_area(void *dummy, addr_t start,
>                                 addr_t len, bool valid)
> --- syslinux-3.82.orig//core/highmem.inc        2009-06-09 13:19:25.000000000 -0400
> +++ syslinux-3.82/core/highmem.inc      2012-06-03 11:14:04.000000000 -0400
> @@ -38,7 +38,7 @@
>  ; report main memory as multiple contiguous ranges...
>  ;
>  get_e820:
> -               mov dword [E820Max],-(1 << 20)  ; Max amount of high memory
> +               mov dword [E820Max],(1 << 30)   ; Max amount of high memory
>                 mov dword [E820Mem],(1 << 20)   ; End of detected high memory
>  .start_over:
>                 mov di,E820Buf
> 
> 
> but he's looking into making it configurable.
> 

Yes, that is the two locations I mentioned.  The configuration is very
difficult since the memory allocator is used before the config file is
read, and in upcoming Syslinux versions will be used even earlier.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.