On 03/09/2013 03:39 AM, Yinghai Lu wrote: > [ Add more to To list ] > > On Fri, Mar 8, 2013 at 10:24 AM, Yinghai Lu <yinghai at kernel.org> wrote: >> On Fri, Mar 8, 2013 at 4:12 AM, WANG Chao <chaowang at redhat.com> wrote: >> >>>> what is 00:02.0 in your system? >>> This IOMMU issue is related to https://lkml.org/lkml/2012/11/26/814. We can >>> discuss this IOMMU issue in that thread. >>> Anyway 00:02.0 is a video card, the box is Ivy Bridge. >>> # lspci -s 00:02.0 -v >>> 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor >>> Graphics Controller (rev 09) (prog-if 00 [VGA controller]) >>> Subsystem: Intel Corporation Device 2211 >>> Flags: bus master, fast devsel, latency 0, IRQ 44 >>> Memory at afc00000 (64-bit, non-prefetchable) [size=4M] >>> Memory at c0000000 (64-bit, prefetchable) [size=256M] >>> I/O ports at 6000 [size=64] >>> Expansion ROM at <unassigned> [disabled] >>> Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit- >>> Capabilities: [d0] Power Management version 2 >>> Capabilities: [a4] PCI Advanced Features >>> Kernel driver in use: i915 >> >> disable drm for i915 will make your iommu work with dump? >> >>> >>> >>> Is it expected to intel_iommu=on or crashkernel_low to make 2nd kernel boot in >>> 3.9? Back in 3.8, it works just fine w/ only crashkernel param. >> >> Yes, I really do not want to set crashkernel low range like 72M >> automatically for all. >> that would have the system with proper iommu support lose 72M under 4G >> in first kernel. >> And can not play allocate and return tricks, as first kernel have no >> idea if iommu will work >> on second kernel even iommu is working on first kernel. >> >> Better to fix iommu support at first. >> >> For old system that does not have DMAR or kernel does not have IOMMU >> support enabled, or >> user does not pass intel_iommu=on. >> We could set crashkernel low range to 72M automatically. > > It seem that it is not worthy to check case that does not support > IOMMU in second kernel. > > Please check attached patch that will just set crashkernel_low auto, and if the > system DO support iommu with kdump, user can specify crashkernel_low=0 > to save low 72M. The patch works flawlessly on my box! Thank you, Yinghai! Let me know if anything else I can help. WANG Chao > > Thanks > > Yinghai >
