nvme: prepare support for Apple NVMe controller
Subsystems (2)
PATCH 1/1 nvme: prepare support for Apple NVMe controller
The Apple NVMe controller found in the Macbook8,1 (12 inch retina model) requires ordered split transfers even on 64bit systems to work. Otherwise, readq() for instance returns all ones, which explains the ridiculous page size of 128MiB reported before.
With this patch applied, the Apple NVMe controller can manually be bound to he NVMe driver. Manual binding is still required since the controller reports a PCI device class of 018002 (mass storage) instead of 010802 (nvme).
---
modprobe nvme
echo "106b 2001" > /sys/bus/pci/drivers/nvme/new_id
Quoted 1 line
From lspci after binding:
| 03:00.0 Mass storage controller: Apple Inc. Device 2001 (rev 01) | Subsystem: Apple Inc. Device 2001 | (...) | Kernel driver in use: nvme
Partitions are correctly recognized and i/o operations seem to work so far.
drivers/block/nvme-core.c | 3 +++ 1 file changed, 3 insertions(+)
drivers/block/nvme-core.c +3 -0
@@ -43,6 +43,9 @@#include <scsi/sg.h> #include <asm-generic/io-64-nonatomic-lo-hi.h> +#define readq lo_hi_readq +#define writeq lo_hi_writeq +#define NVME_MINORS (1U << MINORBITS)#define NVME_Q_DEPTH 1024#define NVME_AQ_DEPTH 256
PATCH 1/1 nvme: prepare support for Apple NVMe controller
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +
Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performance
Christoph recently added a quirks mechanism where I think it would fit
PATCH 1/1 nvme: prepare support for Apple NVMe controller
Hi Stephan,
Thank you! I am glad to see that Linux support for this SSD is workable.
I have a MacBookAir7,1 (11" Macbook Air (Early 2015)) which uses the same (or similar) SSD (PCI ID 106b:2001). I am extremely interested to test the patch on this laptop. Which kernel tree should I apply this patch on? Can I apply it on stable (4.2.5)?
I had thought it might have been something related to initialising the controller because lspci showed correctable errors (DevSta: CorrErr+) on Linux but not on OS X. I also got discouraged because of the vendor-specific PCI class (018002) instead of the nvme PCI class (010802) which indicated a non-standard protocol. It's a nice feeling to know it only requires a quirk to work.
Quoted 14 lines · Jon Derrick
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performanceChristoph recently added a quirks mechanism where I think it would fit
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PATCH 1/1 nvme: prepare support for Apple NVMe controller
Quoted 6 lines · Vedant Lath
Hi Stephan,
Thank you! I am glad to see that Linux support for this SSD is workable.
I have a MacBookAir7,1 (11" Macbook Air (Early 2015)) which uses the same (or similar) SSD (PCI ID 106b:2001). I am extremely interested to
You are right, the latest 11" MacBook Air presumably uses the same controller.
Quoted 2 lines
test the patch on this laptop. Which kernel tree should I apply this patch on? Can I apply it on stable (4.2.5)?
I tested against 4.3-rc7. However, since the patch consits of 2 lines it is very likely that it it also applies to older kernels.
Quoted 7 lines
I had thought it might have been something related to initialising the controller because lspci showed correctable errors (DevSta: CorrErr+) on Linux but not on OS X. I also got discouraged because of the vendor-specific PCI class (018002) instead of the nvme PCI class (010802) which indicated a non-standard protocol. It's a nice feeling to know it only requires a quirk to work.
Do not forget to bind it manually. And there is still a long way, at least for the MacBook8,1 as there is still no clue why the internal keyboard is not working...
Quoted 21 lines · Jon Derrick
Quoted 8 lines
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performanceQuoted 6 lines
Christoph recently added a quirks mechanism where I think it would fit
_______________________________________________
Linux-nvme mailing list
Linux-nvme at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme_______________________________________________
Linux-nvme mailing list
Linux-nvme at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme
PATCH 1/1 nvme: prepare support for Apple NVMe controller
Quoted 11 lines · Stephan G?nther
Quoted 6 lines · Vedant Lath
Hi Stephan,
Thank you! I am glad to see that Linux support for this SSD is workable.
I have a MacBookAir7,1 (11" Macbook Air (Early 2015)) which uses the same (or similar) SSD (PCI ID 106b:2001). I am extremely interested to
You are right, the latest 11" MacBook Air presumably uses the same controller.
To be more precise, the 11" MacBook Air with the 256 GB SSD uses the same controller. The 128 GB models use AHCI. The iFixit teardown is of the 128 GB model which has a Marvell AHCI controller in its SSD.
Quoted 5 lines
Quoted 2 lines
test the patch on this laptop. Which kernel tree should I apply this patch on? Can I apply it on stable (4.2.5)?
I tested against 4.3-rc7. However, since the patch consits of 2 lines it is very likely that it it also applies to older kernels.
I have tested it against 4.3-rc7 and it works. Thank you. :)
Most nvme-cli commands also work fine on it. I have posted some output at http://pastebin.ubuntu.com/13049434/ .
However, nvme-cli show-regs is also affected by the same quirk and reports some incorrect values from BAR0:
$ sudo ./nvme show-regs /dev/nvme0 cap : ffffffffffffffff version : 10001 intms : 0 intmc : 0 cc : 460001 csts : 1 nssr : 0 aqa : ff00ff asq : ffffffffffffffff acq : ffffffffffffffff cmbloc : 0 cmbsz : 0
Quoted 11 lines
Quoted 7 lines
I had thought it might have been something related to initialising the controller because lspci showed correctable errors (DevSta: CorrErr+) on Linux but not on OS X. I also got discouraged because of the vendor-specific PCI class (018002) instead of the nvme PCI class (010802) which indicated a non-standard protocol. It's a nice feeling to know it only requires a quirk to work.
Do not forget to bind it manually. And there is still a long way, at least for the MacBook8,1 as there is still no clue why the internal keyboard is not working...
PATCH 1/1 nvme: prepare support for Apple NVMe controller
In reply to Jon DerrickQuoted 7 lines · Jon Derrick
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performance
Yep.
Quoted 2 lines
Christoph recently added a quirks mechanism where I think it would fit
To be honest we don't know what mechanism you are referring to. Please give us pointer.
I assume that we concur that this workaround--as well as making the nvme driver claim the Apple controller--should be a runtime-decisions based on the device id. That avoids both penalties in terms of cpu cycles and the tedious manual binding.
How to do that sanely is a bit unclear to me. Detection at runtime would require that
1) the nvme driver attempts to bind to non-nvme devices (pci class 018002),
2) checks whether or not that is Apples special controller (106b 2001), and in that case
3) binds to the device while using ordered split writes on 64bit platforms, which probably requires a set of function pointers to low-level ops.
Another approach might be to write an intermediate driver that relies on the nvme driver but encapsulates the remaining stuff.
If Apple's controller is expected to be the only exception, the latter approach would make sense. But I don't believe that Apple builds the only custom nvme controller that is "almost" compatible. (assuming that 018002 instead of 010802 isn't a typo anyways).
Best,
Stephan
PATCH 1/1 nvme: prepare support for Apple NVMe controller
Quoted 5 lines · Stephan G?nther
Quoted 1 line · Jon Derrick
Christoph recently added a quirks mechanism where I think it would fit
To be honest we don't know what mechanism you are referring to. Please give us pointer.
It's new, not merged in an official tree. A copy is on the mailing list somewhere. I committed it to my personal tree here:
Quoted 4 lines
I assume that we concur that this workaround--as well as making the nvme driver claim the Apple controller--should be a runtime-decisions based on the device id. That avoids both penalties in terms of cpu cycles and the tedious manual binding.
Just append the Vendor + Device to struct pci_device_id nvme_id_table if the 64 bit register access really is the only problem preventing it from working in an NVMe compliant way. You can check at run time for the lo_hi_[read/write]q quirk.
If it really works with only this one change to the nvme driver, I also wonder Apple typo'ed their class code.
PATCH 1/1 nvme: prepare support for Apple NVMe controller
Quoted 17 lines · Keith Busch
Quoted 5 lines · Stephan G?nther
Quoted 1 line · Jon Derrick
Christoph recently added a quirks mechanism where I think it would fit
To be honest we don't know what mechanism you are referring to. Please give us pointer.
It's new, not merged in an official tree. A copy is on the mailing list somewhere. I committed it to my personal tree here:
Quoted 4 lines
I assume that we concur that this workaround--as well as making the nvme driver claim the Apple controller--should be a runtime-decisions based on the device id. That avoids both penalties in terms of cpu cycles and the tedious manual binding.
Quoted 4 lines
Just append the Vendor + Device to struct
pci_device_idnvme_id_tableif the 64 bit register access really is the only problem preventing it from working in an NVMe compliant way. You can check at run time for the lo_hi_[read/write]q quirk.
Great, I will give this a try.
Quoted 3 lines
If it really works with only this one change to the nvme driver, I also wonder Apple typo'ed their class code.
The only thing that prevents me from wiping the ssd and debootstrapping is the problem with the internal keyboard. That's another story but I'm looking into that.
Now that there is a way to get the controller working (read/write was ok when I tested it on the Macbook's EFI partition), we will hopefully have some answers soon.
Of course everyone should make some backups before trying that... I did not test anything else than writing a couple of text files to the device, syncing and deleting the files afterwards.
Best,
Stephan
PATCH 1/1 nvme: prepare support for Apple NVMe controller
In reply to Jon DerrickQuoted 9 lines · Jon Derrick
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performanceChristoph recently added a quirks mechanism where I think it would fit
We never access 64 bit registers in the fast path. I'd be fine to apply the patch from Stephan as-is as long as we document in detail why we are doing this. Stephan, can you respin the patch with a comment and also with the PCI ID for the Apple controller added to the ID table?
PATCH 1/1 nvme: prepare support for Apple NVMe controller
Quoted 9 lines · Christoph Hellwig
Quoted 8 lines · Jon Derrick
drivers/block/nvme-core.c line 48
Quoted 3 lines
drivers/block/nvme-core.c +3
-0+#define readq lo_hi_readq +#define writeq lo_hi_writeq +Good job figuring that one out. But this should be a quirk:
a) It will sacrifice some io cycles on other devices
b) It may get lost at some point in the name of performance
Quoted 6 lines
Quoted 1 line
Christoph recently added a quirks mechanism where I think it would fit
We never access 64 bit registers in the fast path. I'd be fine to apply the patch from Stephan as-is as long as we document in detail why we are doing this. Stephan, can you respin the patch with a comment and also with the PCI ID for the Apple controller added to the ID table?
We are testing the new version of the patch and will submit it afterwards.