Re: [Xen-devel] Re: [Xen-users] Hypervisor hangs on startup, 2.6.32-5-xen dom0 kernel panic

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Dec 21, 2010 at 01:13:29PM +0000, Ian Campbell wrote:
> On Mon, 2010-12-20 at 20:18 +0000, Pasi Kärkkäinen wrote:
> > > > [    6.122370] Initializing CPU#0
> > > > [    6.131080] DMA: Placing 64MB software IO TLB between 
> > > > ffff880020000000 - ffff880024000000
> > > > [    6.131087] DMA: software IO TLB at phys 0x20000000 - 0x24000000
> > > > [    6.131090] xen_swiotlb_fixup: buf=ffff880020000000 size=67108864
> > > > [    6.139836] Kernel panic - not syncing: DMA(-12): Failed to exchange 
> > > > pages allocated for DMA with Xen! We either don't have the permission 
> > > > or you do not !
> 
> This suggests that the xen_exchange_memory hypercall has failed for some
> reason.
> 
> -12 is -ENOMEM but size is only 64M and this is start of day so I can't
> think why this would be the case (or at least why it wouldn't always be
> the case if it was happening at all).
> 
> Might be worth trying the dom0_mem hypervisor parameter to limit the
> initial size of dom0, perhaps to 32G.

His 'node_to_dma32' ended being 0 and 62 respectivly. Not enough to allocate
the 64MB SWIOTLB buffer. Isn't there some logic in the Xen hypervisor to 
leave some swath of memory for DMA32?
> 
> Ian.
> 
> > > > [    6.139838]
> > > > [    6.139845] Pid: 0, comm: swapper Not tainted 2.6.32-5-xen-amd64 #1
> > > > [    6.139847] Call Trace:
> > > > [    6.139856]  [<ffffffff8130a9fa>] ? panic+0x86/0x143
> > > > [    6.139862]  [<ffffffff8100ecdf>] ? xen_restore_fl_direct_end+0x0/0x1
> > > > [    6.139867]  [<ffffffff8130c8b2>] ? _spin_unlock_irqrestore+0xd/0xe
> > > > [    6.139871]  [<ffffffff8100d5e5>] ? 
> > > > xen_create_contiguous_region+0xc8/0xe1
> > > > [    6.139878]  [<ffffffff8119d4ba>] ? xen_swiotlb_fixup+0x8b/0xba
> > > > [    6.139882]  [<ffffffff813129f3>] ? _etext+0x0/0x1f360d
> > > > [    6.139887]  [<ffffffff8152b430>] ? xen_swiotlb_init+0x5c/0x5f
> > > > [    6.139891]  [<ffffffff81509fbb>] ? pci_xen_swiotlb_init+0x17/0x24
> > > > [    6.139895]  [<ffffffff8150ce7f>] ? pci_iommu_alloc+0x72/0x78
> > > > [    6.139900]  [<ffffffff8151b14c>] ? mem_init+0x15/0xe5
> > > > [    6.139904]  [<ffffffff81506af7>] ? start_kernel+0x202/0x3e8
> > > > [    6.139908]  [<ffffffff81508c87>] ? xen_start_kernel+0x586/0x58a
> > > > (XEN) Domain 0 crashed: rebooting machine in 5 seconds. 
> 
> 
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