RFC on Kdump and PCIe on ARM64

Sinan Kaya okaya at codeaurora.org
Fri Mar 2 06:12:29 PST 2018

Hi Will,

On 3/2/2018 5:30 AM, Will Deacon wrote:
>> Do you really have to reset the IOMMU?  Can you just give it new page
>> tables that start out with all IOVAs from all devices being invalid,
>> then add valid mappings as drivers need them (presumably after the
>> driver has done whatever it needs to so the device stops using the old
>> DMA addresses)?
> We already have the option to do that via the command line using the
> disable_bypass option, so it just sounds like we need to take this into
> account when resetting the SMMU to take care that GBPA is configured so
> that transactions are terminated when SMMUEN=0.

How about the points that Baoquan highlighted in his email regarding the
solution from AMD and X86?

I have not read the entire thread but, is this just a matter of following
what Bjorn recommended or there is more to it?


Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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