> On Mar 1, 2021, at 11:02 AM, Luck, Tony <tony.luck@xxxxxxxxx> wrote: > > >> >> Some programs may use read(2), write(2), etc as ways to check if >> memory is valid without getting a signal. They might not want >> signals, which means that this feature might need to be configurable. > > That sounds like an appalling hack. If users need such a mechanism > we should create some better way to do that. > Appalling hack or not, it works. So, if we’re going to send a signal to user code that looks like it originated from a bina fide architectural recoverable fault, it needs to be recoverable. A load from a failed NVDIMM page is such a fault. A *kernel* load is not. So we need to distinguish it somehow. > An aeon ago ACPI created the RASF table as a way for the OS to > ask the platform to scan a block of physical memory using the patrol > scrubber in the memory controller. I never did anything with it in Linux > because it was just too complex and didn't know of any use cases. > > Users would want to check virtual addresses. Perhaps some new > option MADV_CHECKFORPOISON to madvise(2) ? > > -Tony
