Re: [Linux-nvdimm] [PATCH] SQUASHME: Fixes to e820 handling of pmem

On Wed, Apr 01, 2015 at 05:25:22PM +0300, Boaz Harrosh wrote: > pfn = PFN_DOWN(ei->addr + ei->size); > > - switch (ei->type) { > - case E820_RAM: > - case E820_PRAM: > - case E820_RESERVED_KERN: > - break; > - default: > + if (ei->type != E820_RAM && ei->type != E820_RESERVED_KERN) > register_nosave_region(PFN_UP(ei->addr), pfn); > - } I guess this makes sense - if the content is persistent already we don't need to save it. > - if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) { > - if (e820.map[i].type != E820_PRAM) > - res->flags |= IORESOURCE_BUSY; > + if (((e820.map[i].type != E820_RESERVED) && > + (e820.map[i].type != E820_PRAM)) || > + res->start < (1ULL<<20)) { So now we also trigger for PRAM regions under 1ULL<<20, was that the intentional change? Honestly I don't really understand this 1ULL<<20 magic here even for the existing case. Guess this is magic from the old ISA PC days? > + res->flags |= IORESOURCE_BUSY; Guess this is the real change, and I'd love to understand why this makes a difference for you. IORESOURCE_BUSY is checked almost never, and is intented to mean it's a driver mapping.