can't access RAM from PCIe device in Xeon

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can't access RAM from PCIe device in Xeon

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Hello,

Is there an known issue of access Xeon's RAM from PCIe (DMA access) ? We observe the issue when using linux 4.x on E5 servers ?
We have this issue only with Xeon E5 + Linux, and using other Intel's chip there is no issue.
When we use the same BIOS, Chip, with windows , we manage to access RAM's from PCIe (DMA access).

I've tried to search and asked the question, but got no response.
Is it a known issue in this chip ? Why is it observed with Linux , but not with Windows ?
Should I upgrade BIOS or is it some BIOS parameter that I should configure ?

We also tried to get assistance from Intel's and from Linux kernel, but nothing helped understanding this issue.
https://bugzilla.kernel.org/show_bug.cgi?id=205701

We are struggling with this issue for a long time now,

Any suggestion about this issue will help,

Ran

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