Re: [PATCH v17 02/10] x86: kdump: make the lower bound of crash kernel reservation consistent

Catalin Marinas
2021-12-14T19:24:29Z

On Tue, Dec 14, 2021 at 08:07:58PM +0100, Borislav Petkov wrote:
> On Fri, Dec 10, 2021 at 02:55:25PM +0800, Zhen Lei wrote:
> > From: Chen Zhou <chenzhou10@huawei.com>
> >
> > The lower bounds of crash kernel reservation and crash kernel low
> > reservation are different, use the consistent value CRASH_ALIGN.
>
> A big WHY is missing here to explain why the lower bound of the
> allocation range needs to be 16M and why was 0 wrong?

I asked the same here:

https://lore.kernel.org/r/20210224143547.GB28965@arm.com

IIRC Baoquan said that there is a 1MB reserved for x86 anyway in the
lower part, so that's equivalent in practice to starting from
CRASH_ALIGN.

Anyway, I agree the commit log should describe this.

--
Catalin