Adding a NVMe custom driver for Target emulation

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storequant2
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Adding a NVMe custom driver for Target emulation

Post by storequant2 » Thu Apr 18, 2024 4:50 pm

Hello, i am just wondering if driver's development is possible on the newest release of VMS for x86. I have an implementation of SCSI and NVMe target server on Linux and want to port it on VMS for test purpose and make it freely available for community. I have only found some old books about VMS Alpha driver's development.

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Re: Adding a NVMe custom driver for Target emulation

Post by arne_v » Thu Apr 18, 2024 6:48 pm

I know absolutely nothing about driver development on VMS.

But I would expect the OS side of drivers on VMS x86-64 to be very similar to VMS Alpha, because even at that level then VMS is supposed to be VMS.

Obviously the HW side of drivers may be different, but it sounds like you got that part covered.
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Re: Adding a NVMe custom driver for Target emulation

Post by reinhardtjh » Fri Apr 19, 2024 5:30 am

In the Release Notes for both V9.2-1 and V9.2-2 there is a section titled "Features not available in VSI OpenVMS x86-64..." Both state that the following are NOT available:

Support for privileged applications, such as:
• User-written device drivers
• Code that directly calls internal system routines (such as those that manage page tables)

See Section 2.1.2 in V9.2-1 and Section 2.2.3 in V9.2-2 Release Notes.

Obviously VSI has written device drivers but apparently it may involve portions of OpenVMS that aren't available yet to the general users. Hopefully it will be soon.
John H. Reinhardt
  • VMS user since 1981

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Re: Adding a NVMe custom driver for Target emulation

Post by arne_v » Fri Apr 19, 2024 10:21 am

Maybe it is just a support issue. VMS currently only supports VM's not physical HW. And the VM can expose a generic SATA disk to VMS not caring about what the virtual disk actually reside on. At least for type 2 hypervisors. Can a type 1 hypervisor access disks directly with a driver that needs to actually match the type of disk?
Arne
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