Messages in this thread | | | Subject | Re: Unable to handle kernel NULL pointer... on cat /proc/pci | Date | Thu, 25 Sep 1997 16:57:32 +0200 (MET DST) | From | (Rogier Wolff) |
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Gabriel Paubert wrote:
> Perhaps in theory but not in practice, you pass the address of a random > value. Either the BIOS sets an error return code and does not modify the > result, or it does not check and it writes all ones to the return value. > However, in this case the BIOS modifies the return value, and it should be > set 0xffffffff if the device is not present. The fact that only 1 or 2 > bits are wrong more likely indicates a hardware problem than anything else.
I expect the 0xffffffff to be a "read of an non-driven bus". This usually turns out to lead to the value <all ones> however bit-errors are allowed: nobody drove the bus.
On the other hand, you're saying there is a well-defined error mechanism to detect non-present devices..... Maybe some chipsets don't consider it important to implement that for configuration space?
Roger.
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