Is it possible to use PCIe SSD as pmem device??

[Jangyong Lee]

 Hi, all.

 Recently, I study about NVML.

 Meanwhile, I wondering whether that is possible to use pcie type device as pmem device.

 If pcie device is registered to NFIT, is it possible to use pcie device as pmem device??
 

[Dan Williams]

No, it can't. The problem is that a device on the PCI-E bus is not DMA
coherent. There are some limited scenarios where it will give the
impression that it works, but it can lead to data corruption in the
general case when you start to consider that any memory mapping might
also be subjected to direct-I/O and 3rd party DMA.

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[Jangyong Lee]

 Thank you for reply.

 If then, Is it possible to use management mode & block device mode except dax mode??


2017년 8월 8일 화요일 오후 1시 42분 33초 UTC+9, Dan Williams 님의 말:

[Dan Williams]

Operating as a block-device is the default for a PCI-E SSD, no need
for an NFIT at all.

> https://groups.google.com/d/msgid/pmem/df2ed6a1-629f-4b6c-ac79-ecd9a31faa78%40googlegroups.com.

[Jangyong Lee]

 Yes. I know that. But, I mean just for test :D

2017년 8월 9일 수요일 오전 1시 38분 27초 UTC+9, Dan Williams 님의 말:

[Dan Williams]

For "just a test" you can specify any physical address range that you
want and treat it as pmem with the "memmap=ss!nn" kernel parameter.
See: https://nvdimm.wiki.kernel.org/

Whether it causes data corruption or not depends on whether you
specify a valid physical address range that can behave as system
memory.

> https://groups.google.com/d/msgid/pmem/64f638f8-9096-48a0-b392-46a536c28478%40googlegroups.com.

[Jangyong Lee]

 OK. Thanks a lot! :D

2017년 8월 9일 수요일 오전 8시 17분 33초 UTC+9, Dan Williams 님의 말: