Hi,
I've sent this to the wrong maintainer by mistake (sorry about that)
so I going to re-post it again in a moment.
FYI
Thanks,
Yigal
On Sun, Jun 19, 2016 at 7:40 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Sun, Jun 19, 2016 at 5:49 AM, Yigal Korman <yigal@xxxxxxxxxxxxx> wrote:
>> Before this patch, passing a range that is beyond the physical memory
>> range will succeed, the user will see a /dev/pmem0 and will be able to
>> access it. Reads will always return 0 and writes will be silently
>> ignored.
>>
>> I've gotten more than one bug report about mkfs.{xfs,ext4} or nvml
>> failing that were eventually tracked down to be wrong values passed to
>> memmap.
>>
>> This patch prevents the above issue by instead of adding a new memory
>> range, only update a RAM memory range with the PRAM type. This way,
>> passing the wrong memmap will either not give you a pmem at all or give
>> you a smaller one that actually has RAM behind it.
>>
>> And if someone still needs to fake a pmem that doesn't have RAM behind
>> it, they can simply do memmap=XX@YY,XX!YY.
>
> Thanks! I've debugged a report like this as well.
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