Mikulas,
Can you send me a link to this driver. I need to implement a "real" and "correct" driver for a PMC Sierra card, so I need to pay attention to the atomic issue you described.
Doug Dumitru
EasyCo LLC
On Fri, Jun 19, 2015 at 9:33 AM, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
Hi
I looked at the new the persistent memory block device driver
(drivers/block/pmem.c and arch/x86/kernel/pmem.c) and it seems that the
interface between them is incorrect.
If I want to use persistent memory in another driver, for a different
purpose, how can I make sure that that drivers/block/pmem.c doesn't attach
to this piece of memory and export it? It seems not possible.
drivers/block/pmem.c attaches to everything without regard that there may
be other users of persistent memory.
I think a correct solution would be to add a partition table at the
beginning of persistent memory area and this partition table would
describe which parts belong to which programs - so that different programs
could use persistent memory and not step over each other's data. Is there
some effort to standardize the partition table ongoing?
BTW. some journaling filesystems assume that 512-byte sector is written
atomically. drivers/block/pmem.c breaks this requirement. Persistent
memory only gurantees 8-byte atomic writes.
Mikulas
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Doug Dumitru
EasyCo LLC
EasyCo LLC
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