On 01/22/2013 09:20 AM, Thomas Renninger wrote:
> From: Yinghai Lu <[email protected]>
>
> kdump voided the whole original e820 map and half way made
> it up via memmap= options passed via kdump boot params again.
>
> But this is conceptionally wrong. The whole original memory ranges
> which are declared reserved, ACPI data/nvs or however are not usable
> must stay the same and get honored by the kdump kernel.
>
> Therefore memmap=resetusablemap gets introduced.
> kdump passes this one and only the usable e820 ranges are removed.
> kdump passes the usable ranges to use via memmap=x@y parameter(s).
> The not usable e820 ranges are preserved.
>
> This for example fixes mmconf (extended PCI config access) and
> possibly other kernel parts which rely on remapped memory to be
> in reserved or ACPI (data/nvs) declared e820 memory areas.
>
> Tested-by: Thomas Renninger <[email protected]>
> Reviewed-by: Thomas Renninger <[email protected]>
> Signed-off-by: Thomas Renninger <[email protected]>
Tested-by: and Reviewed-by: are rather redundant with Signed-off-by:.
Also, you should have a Signed-off-by: from the author (Yinghai).
However, when thinking about it this really doesn't seem to be the right
interface, either. Something like "memmap=reserveram" which turns all
RAM areas into reserved areas, which can then be overridden by memmap=
options would make more sense.
Even more sense would be to pass the modified memmap to kexec...
-hpa
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