Ask for help about the smmu initialization process in the kdump crash kernel

[Liu Song]

Hi

We encountered such a problem in our environment. When a kernel panic 
occurs,
the DPU still has access to the host device under the kdump crash 
kernel, but the
content of the smmu has been cleared during the startup of the crash 
kernel, thus
causing errors. Referring to the implementation of X86 here, it will 
judge whether is
a crash kernel, and if it is, it will copy the previous IOMMU page table 
content.

What we want to ask is whether arm64 can also operate in this way to 
maintain the
previous page table content of the device under the crash kernel, and 
are there any
problems that cannot be solved by the smmu mechanism in the implementation?


Thanks