Using Intel Xeon computer with linux kernel 4.18.0 centos8. Trying to access RAM (with DMA) using FPGA fails in this computer. 1. I tried to add intel_iommu=off - it did not help. 2. Installing windows on same PC - FPGA can access RAM using DMA without issues. 3. using another PC (Intel Duo) with same linux and OS - FPGA access works. FPGA access the RAM using a physical address provided by a kernel module which allocates physical continuous memory in PC. (the module works perfectly with Intel Duo on exactly same OS and kernel).
Created attachment 286117 [details] dmesg v4.18.0 dmesg.log from Ranran
Created attachment 286119 [details] dmesg v4.18.0 intel_iommu=off dmesg_intel_iommu_off.log from Ranran
please see module driver here: https://docs.google.com/document/d/1LlqTnfoqdmwABrR6xOAPlQOzDw1aGjS5hhNI61IwULw/edit?usp=sharing Thanks
Hi, 1. Trying to disable Virtualization did not help.... 2. result for lspci : https://docs.google.com/document/d/1gE4Ba4UmuVJRVRVl4JvsDUy8gXJYtPKuUOpC2eUL14M/edit?usp=sharing Thanks
Hello, I have tried to upgrade to latest kernel 5.4 (elrepo in centos), but with this processor/board (system x3650, Xeon), it get hang during kernel boot, without any error in dmesg, just keeps waiting for nothing for couple of minutes and than drops to dracut. I am really stuck with this, is there any way to get progress with this bug ? Please help, Ran
Created attachment 286201 [details] lspci The lspci mentioned in comment #4. Attached in bugzilla to prevent the link in comment #4 from becoming stale, e.g., if the owner deletes the Google Document, the link will no longer work.
Created attachment 286203 [details] test_module.c This is the module mentioned in comment #3.