Re: [PATCH 1/3] e820_update_range(): Strip size of original region

[Yinghai Lu]

On Tue, Jun 24, 2008 at 7:35 AM, Bernhard Walle <bwalle@xxxxxxx> wrote:
> This patch fixes a bug in e820_update_range(): Previously, if a region was
> partially covered, then e820_update_range() only added a new E820 range but
> didn't update the end/size of the previous range. That lead to duplicate
> covering of a region.
>
> Patch tested on i386 and x86-64 with patch that uses e820_update_range()
> to limit the E820 map when "mem" parameter is specified on the command line.
>
>
> Signed-off-by: Bernhard Walle <bwalle@xxxxxxx>
> ---
>  arch/x86/kernel/e820.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index e285ea3..e466073 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -422,6 +422,7 @@ u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
>                final_end = min(start + size, ei->addr + ei->size);
>                if (final_start >= final_end)
>                        continue;
> +               ei->size -= final_end - final_start;
>                e820_add_region(final_start, final_end - final_start,
>                                         new_type);
>                real_updated_size += final_end - final_start;
> --

thanks for finding it, but fix is not complete. could have problem
with fore boundary overlapping. need to update the ei->addr

please check attached patch

YH
[PATCH] x86: fix e820_update_range size when overlapping

before that we relay on sanitize_e820_map to remove the overlap.

but e820_update_range(,,E820_RESERVED, E820_RAM) will not work

this patch fix that

who is going to use this?

Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 512f779..15b4393 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -425,6 +425,11 @@ u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
 		e820_add_region(final_start, final_end - final_start,
 					 new_type);
 		real_updated_size += final_end - final_start;
+
+		ei->size -= final_end - final_start;
+		if (ei->addr < final_start)
+			continue;
+		ei->addr = final_end;
 	}
 	return real_updated_size;
 }