[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] floppy not working in Linux
We had a report that the floppy driver isn't working with current Xen. While certainly not a major concern to most of us, it still seems odd that this simple a piece of hard-/software wouldn't work under Xen, especially as it is known that it had been working a couple of years back. Trying to debug the issue has surfaced quite a perhaps strange mix of observations: - On an old (32-bit) box of mine I found that the driver would work on Xen 3.1, while the same kernel running on top of 3.2.x would not work (nor would a reasonably current kernel on a reasonably current Xen). - On both this old and not too old a 64-bit box I found that removing the REALLY_SLOW_IO definition at the top of floppy.c would reduce the amount of errors encountered quite significantly. Specifically, I have never seen a mount fail with that change in place (but there are occasional errors logged by the driver). - Generally, the problems start with unexpected interrupts or, less frequently, "-- FDC reply error" messages. While the driver certainly didn't change much over the last couple of years, the effect of the adjustment above suggests that the driver itself may have problems which are just unnoticeable when run on bare hardware. Given the timing requirements to service the FDC (a maximum of about 120us when using the FIFO optimally) I wonder whether it is reasonable to expect this to work reliably at all, especially when guest domains are consuming non-neglectable amounts of CPU time. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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