[arch-general] LUKS, SD card reader and initramfs

[Mauro Santos]

I have a setup where I use LVM on LUKS to encrypt all system partitions
(except /boot of course). Currently I have to input the LUKS password
every time to unlock the volume, I wanted to be able to get the key from
an SD card(1) so I don't have to type the password every single time,
but I've run into a problem I haven't been able to solve and I'm out of
ideas.

Here is what I've done/tried.

I have got myself an SD card and confirmed it works fine before trying
anything else.

I have setup everything according to the wiki to store the key between
the MBR and first partition.

I've added the cryptkey= entry in the kernel command line.

I've added the card reader drivers to the MODULES line in
/etc/mkinitcpio.conf and rebuilt the initramfs. I've confirmed that the
modules have been added.

Rebooted to try it out. This is where the problems start, once the
drivers for the card reader get loaded I get spammed with messages like:

mmcblk0: error -110 transferring data, sector 0, nr 8, cmd response
0x900, card status 0xb00

mmcblk0: error -110 transferring data, sector 1, nr 7, cmd response
0x900, card status 0x0

end_request: I/O error, dev mmcblk0, sector 1

Buffer I/O error on device mmcblk0, logical block 0

This happens even if I don't try to access the card to get the
encryption key. The messages only stop after I remove the card.

The drivers I have explicitly included in the initramfs are: sdhci-pci
and mmc_block. sdhci and mmc_core get pulled as a dependencies of
sdhci-pci. I have also tried to include the drivers for the other
modules of the card reader, such as memory stick support and firewire
since they are all hanging on the same controlled but that didn't make
any difference.

Since this works fine after the machine has booted I thought I might
need to include some udev rule, but grepping through the rules I don't
see anything that looks to be needed. The only stuff that comes up is
persistent naming link creation and some udisks{,2} stuff that I suppose
are meant for icon presentation or something like that.

Using 'udevadm monitor' also doesn't show anything that seems to be
special, this is what I get when I insert the card:

KERNEL[7650.629820] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368 (mmc)
KERNEL[7650.631034] add      /devices/virtual/bdi/179:0 (bdi)
UDEV  [7650.633731] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368 (mmc)
KERNEL[7650.634430] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368/block/mmcblk0
(block)
KERNEL[7650.634494] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368/block/mmcblk0/mmcblk0p1
(block)
UDEV  [7650.635568] add      /devices/virtual/bdi/179:0 (bdi)
UDEV  [7650.747593] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368/block/mmcblk0
(block)
UDEV  [7650.866726] add
/devices/pci0000:00/0000:00:14.4/0000:07:01.1/mmc_host/mmc0/mmc0:b368/block/mmcblk0/mmcblk0p1
(block)

The hardware:
> lspci -v -s 07:01
07:01.0 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller
(rev 05) (prog-if 10 [OHCI])
	Subsystem: Packard Bell B.V. Device c109
	Flags: bus master, medium devsel, latency 64, IRQ 21
	Memory at feaff800 (32-bit, non-prefetchable) [size=2K]
	Capabilities: <access denied>
	Kernel driver in use: firewire_ohci

07:01.1 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro
Host Adapter (rev 22)
	Subsystem: Packard Bell B.V. Device c109
	Flags: bus master, medium devsel, latency 64, IRQ 22
	Memory at feaff400 (32-bit, non-prefetchable) [size=256]
	Capabilities: <access denied>
	Kernel driver in use: sdhci-pci

07:01.2 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host
Adapter (rev 12)
	Subsystem: Packard Bell B.V. Device c109
	Flags: bus master, medium devsel, latency 64, IRQ 22
	Memory at feafec00 (32-bit, non-prefetchable) [size=256]
	Capabilities: <access denied>
	Kernel driver in use: r592

I'm all out of ideas, any help will be appreciated.

(1) Why SD card? Because my laptop has a card reader and by using it I
don't need to occupy a USB port, so when I'm at home I could insert the
SD card and forget about it, then when I take the laptop out I don't
carry the card with me or I remove it as soon as it isn't needed.

-- 
Mauro Santos