Messages in this thread | | | Date | Mon, 11 Mar 2013 10:48:53 -0400 | From | Vivek Goyal <> | Subject | Re: [PATCH] x86, kdump: Set crashkernel_low automatically |
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On Sun, Mar 10, 2013 at 09:56:57PM -0700, Yinghai Lu wrote: > Current code does not set low range for crashkernel if the user > does not specify that. > > That cause regressions on system that does not support intel_iommu > properly. > > Chao said that his system does work well on 3.8 without extra parameter. > even iommu does not work with kdump. > > Set crashkernel_low automatically if the user does not specify that. > > For system that does support IOMMU with kdump properly, user could > specify crashkernel_low=0 to save that 72M low ram. >
Hi Yinghai,
Had a question about crashkernel_auto_low. So this is the amount of memory rerved under 4G. I am not very clear about the semantics here.
So by default memory wil always come from areas above 4G (when crashkernel=X specified) and if user needs reserveation in lower memory area, it needs to be sepcified explicitly using crashkernel_low?
But will that not break the case of exising bzImage which are 32bit. They currently work if I specify crashkernel=256M. Now suddenly memory will come from higher addresses and 32bit bzImage can't be loaded there. Or I understood the syntax part wrong.
P.S. Explanation in kernel-parameters.txt is really short. Can you please add some explanation in kdump.txt to clarify how crashkernel_low is supposed to be used.
Thanks Vivek
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