On Sun, 2013-08-11 at 23:13 +0200, Rafael J. Wysocki wrote: > On Thursday, August 08, 2013 04:50:42 PM Toshi Kani wrote: > > On Fri, 2013-08-09 at 00:12 +0200, Rafael J. Wysocki wrote: > > > On Thursday, August 08, 2013 11:15:20 AM Toshi Kani wrote: > > > > On Fri, 2013-08-02 at 18:04 -0600, Toshi Kani wrote: > > > > > On Sat, 2013-08-03 at 01:43 +0200, Rafael J. Wysocki wrote: > > > > > > On Friday, August 02, 2013 03:46:15 PM Toshi Kani wrote: > > > > > > > On Thu, 2013-08-01 at 23:43 +0200, Rafael J. Wysocki wrote: > > > > : > > > > > > > I think it fails with -EINVAL at the place with dev_warn(dev, "ACPI > > > > > > > handle is already set\n"). When two ACPI memory objects associate with > > > > > > > a same memory block, the bind procedure of the 2nd ACPI memory object > > > > > > > sees that ACPI_HANDLE(dev) is already set to the 1st ACPI memory object. > > > > > > > > > > > > That sound's plausible, but I wonder how we can fix that? > > > > > > > > > > > > There's no way for a single physical device to have two different ACPI > > > > > > "companions". It looks like the memory blocks should be 64 M each in that > > > > > > case. Or we need to create two child devices for each memory block and > > > > > > associate each of them with an ACPI object. That would lead to complications > > > > > > in the user space interface, though. > > > > > > > > > > Right. Even bigger issue is that I do not think __add_pages() and > > > > > __remove_pages() can add / delete a memory chunk that is less than > > > > > 128MB. 128MB is the granularity of them. So, we may just have to fail > > > > > this case gracefully. > > > > > > > > FYI: I have submitted the patch blow to close this part of the issue... > > > > > > > > https://lkml.org/lkml/2013/8/8/396 > > > > > > That looks good to me, but we'd still need to make it possible to have > > > memory blocks smaller than 128 MB ... > > > > Do you mean acpi_bind_one() needs to be able to handle such case? If > > so, it should not be a problem since a memory block device won't be > > created when add_memory() fails with the change above. So, there is no > > binding to be done. If you mean add_memory() needs to be able to handle > > a smaller range, that's quite a tough one unless we make the section > > size smaller. > > > > BTW, when add_memory() fails, the memory hot-add request still succeeds > > with no driver attached. This seems logical, but the added device is > > useless when no handler is attached. And it does not allow ejecting the > > device with no handler. I am not too worry about this since this is a > > rare case, but it reminded me that the framework won't handle rollback. > > I'm not sure which rollback you mean. During removal? I meant rollback during hot-add. Ideally, a device should be either added in usable state (success) or failed back to the original state (rollback). Added in un-usable state is not really a success for users, and creates an odd state to deal with. But it is still a LOT better than crashing the system. So, I think this outcome is reasonable on this framework because adding rollback at this point will complicate the things unnecessarily. > There are two slight problems here in my view. First, even if the device > cannot be ejected directly, it still will be removed when its parent is > ejected, so it may be more consistent to just allow everything to be ejected > regardless of whether or not it has a scan handler. Agreed. > Second, I guess the > removal is undesirable for memory devices for which the registration of the > scan handler failed, so it would be good to fail the "offline" of such devices > regardless of how we get there. That's why I thought it would be good to have > an "offline disabled" flag in struct acpi_device. I see. But when attach() failed, the memory device may not be used by the kernel. So, I think it should be safe to remove it. Thanks, -Toshi -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
