It's a specification for an interface between the boot loader and the operating
system. It's based on the device tree model that exists on PowerPC today.
ePAPR defines a bunch of extensions, including one for hypervisors. The byte
channel concept is an example of that.
Without some kind of mapping, there's no way for an application to know which
/dev entry to open. Each byte channel goes to a different
I don't see how. A byte channel node defines several properties, one of which
could be a text string that acts as a label. So if an application is looking
for the "channel-to-partition-two" byte channel, it can search for that string
in the device tree. Once it finds the matching node, it can extract the byte
channel handle.
At this point, the application will want to open a /dev entry that corresponds
to that byte channel handle. This is the piece I'm missing with the tty layer.
If I want to create a regular character device, I can do this:
bc->dev_id = MKDEV(MAJOR(dev_id), MINOR(dev_id) + i);
device_create(ehv_bc_class, NULL, bc->dev_id, bc, "bc%u", bc->handle);
Here, I control the name of the /dev entry via "bc%u". I want something similar
for tty devices.
I'm not sure I understand that. In order for udev to do this, I need to tell it
what the byte channel handle actually is. How do I do that using the tty layer?
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Timur Tabi
Linux kernel developer at Freescale
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