Messages in this thread | | | Date | Mon, 8 Apr 2013 11:37:06 -0700 | Subject | Re: [PATCH v3 1/4] x86, kdump: Set crashkernel_low automatically | From | Yinghai Lu <> |
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On Mon, Apr 8, 2013 at 12:09 AM, Dave Young <dyoung@redhat.com> wrote: >> We have now modified crashkernel=X to allocate memory beyong 4G (if >> available) and do not allocate low range for crashkernel if the user >> does not specify that with crashkernel_low=Y. This causes regression >> if iommu is not enabled. Without iommu, swiotlb needs to be setup in >> first 4G and there is no low memory available to second kernel. > > Is it possible to reuse the 1st kernel swiotlb region in 2nd capture > kernel if it's available?
If the first kernel is using intel iommu, and swiotlb is freed after intel iommus is enabled in first kernel.
> >> >> 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. > > How about make swiotlb size tunable in 1st kernel as well such as adding > a swiotlb_size= to cmdline, if it's set in 1st kernel crashkernel > reserving code can take it automaticlly. > can not understand this.
Thanks
Yinghai
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