On Fri, Dec 01, 2006 at 02:15:24PM -0700, Eric W. Biederman wrote:
Right. For LinuxBIOS not a problem for earlyprintk in the kernel somethings might need to be refactored. The challenge in the kernel is we don't know at build to how to do a pci_read_config...
The other hard part early in the kernel is the fact that the bar is memory mapped I/O. Which means it will need to get mapped into the kernels page tables.
I see.
And I have some code that barely works for this already, perhaps Eric and I should work together on this :)
I would be interested in having a look at any code for it too.
Sure, I will send it out shortly. I currently have a working user space libusb thing (easy, but useful for my debug)
Hm - for driving which end?
and a rude read/write to the bar from user space program that
How does that work? /dev/{port,mem}?
allowed me to debug the worst of the state machine from user space. I don't think I have the state setup logic correct yet but that is minor in comparison.
I really wish the EHCI spec had made that stupid interface 16 bytes instead of 8 or had a way to chain multiple access together. The we could have used a normal usb cable. As it is most descriptors are 1 byte to big to read.
Which descriptors are you reading?
The debug port isn't really supposed to be used with anything but a debug device - which can't be enumerated normally anyway.
//Peter