Re: [PATCH] kdump: Save parameter segment in protected mode (x86)

From: Eric W. Biederman
Date: Thu Jul 28 2005 - 22:20:19 EST

Ack. This is a simple fix to a very practical problem, for
using the kernel from a reserved area of memory.

Vivek Goyal <vgoyal@xxxxxxxxxx> writes:

> o With introduction of kexec as boot-loader, the assumption that parameter
> segment will always be loaded at lower address than kernel and will be
> addressable by early bootup page tables is no longer valid. In kexec on
> panic case parameter segment might well be loaded beyond kernel image and
> might not be addressable by early boot page tables.
> o This case might hit in the scenario where user has reserved a chunk of
> memory for second kernel, for example 16MB to 64MB, and has also built
> second kernel for physical memory location 16MB. In this case kexec has no
> choice but to load the parameter segment at a higher address than new kernel
> image at safe location where new kernel does not stomp it.
> o Though problem should automatically go away once relocatable kernel for i386
> is in place and kexec can determine the location of new kernel at run time
> and load parameter segment at lower address than kernel image. But till then
> this patch can go in (assuming it does not break something else).
> o This patch moves up the boot parameter saving code. Now boot parameters
> are copied out in protected mode before page tables are initialized. This
> will ensure that parameter segment is always addressable irrespective of
> its physical location.
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at