On Sun, Dec 12, 2021 at 06:48:05AM -0800, Dan Williams wrote:

On Fri, Dec 10, 2021 at 6:05 AM Vivek Goyal [off-list ref] wrote:

quoted

On Thu, Dec 09, 2021 at 07:38:28AM +0100, Christoph Hellwig wrote:

quoted

While using the MC-safe copy routines is rather pointless on a virtual device
like virtiofs,

I was wondering about that. Is it completely pointless.

Typically we are just mapping host page cache into qemu address space.
That shows as virtiofs device pfn in guest and that pfn is mapped into
guest application address space in mmap() call.

Given on host its DRAM, so I would not expect machine check on load side
so there was no need to use machine check safe variant.

That's a broken assumption, DRAM experiences multi-bit ECC errors.
Machine checks, data aborts, etc existed before PMEM.

So the conclusion here is that we should always use the mc safe variant?