On 07/21/15 at 09:38am, Ingo Molnar wrote:
>
> * Dave Young <dyo...@redhat.com> wrote:
>
> > Hi, Baoquan
> >
> > The interface was introduced by Yinghai, ccing him.
>
> Also, why was this syntax introduced in the first place? Why should the user
> care??
The history is like below, I might miss something, Yinghai/HPA/Vivek may correct
and provide more background:
First commit is below:
commit 7d41a8a4a2b2438621a9159477bff36a11d79a42
Author: Yinghai Lu <ying...@kernel.org>
Date: Thu Jan 24 12:20:10 2013 -0800
x86, kdump: Remove crashkernel range find limit for 64bit
Previously kdump reservation is limited to <896M, above commit remove the
limitation.
Then because of kdump kernel need access low mem for swiotlb buffer, thus
there's
commit below:
commit 0212f9159694be61c6bc52e925fa76643e0c1abf
Author: Yinghai Lu <ying...@kernel.org>
Date: Thu Jan 24 12:20:11 2013 -0800
x86: Add Crash kernel low reservation
Later, Vivek found old kexec-tools does not work, then Yinghai introduced new
param
crashkernel_high=:
commit 55a20ee7804ab64ac90bcdd4e2868a42829e2784
Author: Yinghai Lu <ying...@kernel.org>
Date: Mon Apr 15 22:23:47 2013 -0700
x86, kdump: Retore crashkernel= to allocate under 896M
Finally it becomes crashkernel=x,high:
commit adbc742bf78695bb98c79d18c558b61571748b99
Author: Yinghai Lu <ying...@kernel.org>
Date: Mon Apr 15 22:23:48 2013 -0700
x86, kdump: Change crashkernel_high/low= to crashkernel=,high/low
>
> We should only have a single crashkernel option, to enable it - and
> everything
> else should be figured out by the kernel, automatically.
Presonally I do not current complicated params either, I hope we can have an
elegant interface, but seems there's no better way to resolve the low memory
only requirement for software tlb.
>
> Any other sub-options just paper over some fragility elsewhere and make the
> feature harder to use, hence more fragile.
Agree, it is becoming worse..
Thanks
Dave
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