Revision a1a15ac5f9aeee521c048a88fc1aec848e623de7 authored by Kris Shannon on 02 March 2009, 08:47:37 UTC, committed by Jens Axboe on 05 March 2009, 11:04:57 UTC
When booting Xen Dom0 on a pre-release 3.2.1 hypervisor the system Oopses on a "Unable to handle kernel NULL pointer dereference" in xenwatch. From the backtrace it looks like backend_changed is calling bdget_disk with a NULL pointer. Checking for NULL and returning ENODEV instead allows the kernel to boot.
1 parent 559595a
bt8xxgpio.txt
===============================================================
== BT8XXGPIO driver ==
== ==
== A driver for a selfmade cheap BT8xx based PCI GPIO-card ==
== ==
== For advanced documentation, see ==
== http://www.bu3sch.de/btgpio.php ==
===============================================================
A generic digital 24-port PCI GPIO card can be built out of an ordinary
Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The
Brooktree chip is used in old analog Hauppauge WinTV PCI cards. You can easily
find them used for low prices on the net.
The bt8xx chip does have 24 digital GPIO ports.
These ports are accessible via 24 pins on the SMD chip package.
==============================================
== How to physically access the GPIO pins ==
==============================================
The are several ways to access these pins. One might unsolder the whole chip
and put it on a custom PCI board, or one might only unsolder each individual
GPIO pin and solder that to some tiny wire. As the chip package really is tiny
there are some advanced soldering skills needed in any case.
The physical pinouts are drawn in the following ASCII art.
The GPIO pins are marked with G00-G23
G G G G G G G G G G G G G G G G G G
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
---------------------------------------------------------------------------
--| ^ ^ |--
--| pin 86 pin 67 |--
--| |--
--| pin 61 > |-- G18
--| |-- G19
--| |-- G20
--| |-- G21
--| |-- G22
--| pin 56 > |-- G23
--| |--
--| Brooktree 878/879 |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| |--
--| O |--
--| |--
---------------------------------------------------------------------------
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
^
This is pin 1
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