On Wed, 2008-01-09 at 11:26 +1100, Benjamin Herrenschmidt wrote: > > Christoph, > > > > it is generic code, it works by patching the module you load and is in > > no way nvidia specific, I think we should revert your chance > > as the notifiers have a valid user and one it has been planned to upstream.. > > Agreed, it looks like a sane enough user of page fault notifiers, it's > going to be upstream, and it's useful to fight evil binary drivers so > that sounds like a good justification to bring those back in :-)
The fault notifiers are used in a special version of MadWifi (Atheros wireless driver with some non-free parts) to figure out which registers are being accessed. The tracing capability has been essential for the development of the free replacement, ath5k. Considering that ath5k is being developed in the kernel tree, whereas madwifi-trace needs 2.6.23, one needs different kernels for tracing and development. Lifting this requirement would be a time saver for the the developers of ath5k. And once 2.6.24 is released, ath5k developers will be in the position to ask users to downgrade their kernels to get traces for their cards. That's something I'd like to avoid. I looked at ways to implement the page fault handler using kprobes, but I could not find a simple solution. The problem is that kprobes uses the fault notifier for its own needs. I'm still hopeful that somebody with a better understanding of kprobes will be able to implement fault notification without patching the kernel. But if no such solution is found, I would also support reverting the patch that removed fault notifiers on i386. -- Regards, Pavel Roskin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/