Difference between revisions of "Hacks, hints, and tricks"
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Then you can use the i2c utilities to access devices that are in use. | Then you can use the i2c utilities to access devices that are in use. | ||
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| + | ==Linux kernel debugfs== | ||
| + | /sys/kernel/debug | ||
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| + | contains helpful debugging infos. To mount this, use this command (assuming you've compiled in said support): | ||
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| + | mount -tdebugfs none /sys/kernel/debug | ||
=Hints= | =Hints= | ||
Revision as of 08:48, 20 March 2014
A resting place for important technotes that don't fit anywhere else.
Hacks
I2C debugging
The kernel will lock I2C devices, making it impossible to use userspace tools to debug an issue. To get around this, modify drivers/i2c/i2c-dev.c and remove the EBUSY return statement. E.g. there's a function that either returns 0 or -EBUSY, make it always return 0.
Then you can use the i2c utilities to access devices that are in use.
Linux kernel debugfs
/sys/kernel/debug
contains helpful debugging infos. To mount this, use this command (assuming you've compiled in said support):
mount -tdebugfs none /sys/kernel/debug
Hints
Using a serial port
To use a plug-in USB serial port with screen, you need to be part of the "dialup" group.
sudo vigr
And add your username to the end of the "dialup" line
sudo vigr -s
And add your username yet again to the end of the "dialup" line
Exit, and log back in. You should be able to do something like
screen /dev/ttyUSB0 115200
and use the USB serial adapter you just plugged in.
