Kdump kernel hangs when using iommu=soft

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Environment

SUSE Linux Enterprise Server 10 SP2

Situation

SLES10 SP2 in VMWare ESX 3.5 VMs (4vCPU with 8GB) are hanging, when vmlinux has been
booted with iommu=soft. The problem only happens with more than 2vCPUs or 2.5GB of RAM.
When booting with iommu=soft (enabling swiotlb) the kernel will not fit into 64M.

Resolution

To get kdump to work in an ESX VM when vmxnet is in use and the kernel is
booted with iommu=soft:

Configure more crashkernel space. 
Change the default crashkernel=64M@16M to crashkernel=128M@16M

Disclaimer

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