[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Bug] Intel RMRR support with upstream Qemu
Hi, On Fri, 21 Jul 2017 10:57:55 +0000 "Zhang, Xiong Y" <xiong.y.zhang@xxxxxxxxx> wrote: > On an intel skylake machine with upstream qemu, if I add > "rdm=strategy=host, policy=strict" to hvm.cfg, win 8.1 DomU couldn't boot > up and continues reboot. > > Steps to reproduce this issue: > > 1) Boot xen with iommu=1 to enable iommu > 2) hvm.cfg contain: > > builder="hvm" > > memory=xxxx > > disk=['win8.1 img'] > > device_model_override='qemu-system-i386' > > device_model_version='qemu-xen' > > rdm="strategy=host,policy=strict" > > 3) xl cr hvm.cfg > > Conditions to reproduce this issue: > > 1) DomU memory size > the top address of RMRR. Otherwise, this > issue will disappear. > 2) rdm=" strategy=host,policy=strict" should exist > 3) Windows DomU. Linux DomU doesn't have such issue. > 4) Upstream qemu. Traditional qemu doesn't have such issue. > > In this situation, hvmloader will relocate some guest ram below RMRR to > high memory, and it seems window guest access an invalid address. Could > someone give me some suggestions on how to debug this ? You're likely have RMRR range(s) below 2GB boundary. You may try the following: 1. Specify some large 'mmio_hole' value in your domain configuration file, ex. mmio_hole=2560 2. If it won't help, 'xl dmesg' output might come useful Right now upstream QEMU still doesn't support relocation of parts of guest RAM to >4GB boundary if they were overlapped by MMIO ranges. AFAIR forcing allow_memory_relocate to 1 for hvmloader didn't bring anything good for HVM guest. Setting the mmio_hole size manually allows to create a "predefined" memory/MMIO hole layout for both QEMU (via 'max-ram-below-4g') and hvmloader (via a XenStore param), effectively avoiding MMIO/RMRR overlaps or RAM relocation in hvmloader, so this might help. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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