On Thu, Oct 18, 2018 at 3:26 PM Kees Cook <[email protected]> wrote: > > On Thu, Oct 18, 2018 at 3:23 PM, Dan Williams <[email protected]> > wrote: > > On Thu, Oct 18, 2018 at 3:19 PM Kees Cook <[email protected]> wrote: > >> > >> On Thu, Oct 18, 2018 at 2:35 PM, Dan Williams <[email protected]> > >> wrote: > >> > On Thu, Oct 18, 2018 at 1:31 PM Kees Cook <[email protected]> wrote: > > [..] > >> > I cringe at users picking addresses because someone is going to enable > >> > ramoops on top of their persistent memory namespace and wonder why > >> > their filesystem got clobbered. Should attempts to specify an explicit > >> > ramoops range that intersects EfiPersistentMemory fail by default? The > >> > memmap=ss!nn parameter has burned us many times with users picking the > >> > wrong address, so I'd be inclined to hide this ramoops sharp edge from > >> > them. > >> > >> Yeah, this is what I'm trying to solve. I'd like ramoops to find the > >> address itself, but it has to do it really early, so if I can't have > >> nvdimm handle it directly, will having regions already allocated with > >> request_mem_region() "get along" with the rest of nvdimm? > > > > If the filesystem existed on the namespace before the user specified > > the ramoops command line then ramoops will clobber the filesystem and > > the user will only find out when mount later fails. All the kernel > > will say is: > > > > dev_warn(dev, "could not reserve region %pR\n", res); > > > > ...from the pmem driver, and then the only way to figure who the > > conflict is with is to look at /proc/iomem, but the damage is already > > likely done by that point. > > Yeah, bleh. Okay, well, let's just skip this for now, since ramoops > doesn't do _anything_ with pmem now. No need to go crazy right from > the start. Instead, let's make it work "normally", and if someone > needs it for very early boot, they can manually enter the mem_address. > > How should I attach a ramoops_probe() call to pmem?
To me this looks like it would be a nvdimm glue driver whose entire job is to attach to the namespace, fill out some ramoops_platform_data, and then register a "ramoops" platform_device for the ramoops driver to find.
