Paul Gortmaker wrote: > > Test10-pre4 (and up) can die on the new WP test as follows: > > Checking if this processor honours the WP bit even in supervisor mode... > <1>Unable to handle kernel paging request at virtual address c0000000 > > I examined the new WP code added to pre4 and even checked the exception > table entries stored in vmlinux by it and it all looked fine. Strange. > Well after a few handfuls of hair, it turns out that the new WP test code > is a red herring - it just happens to be the first thing to cause a > fault and a lookup in the exception table. > > It turns out that also in pre4 was a patch to use non-continuous > initialization of the elements in kernel_module. And if modules are > enabled, the exception table for the kernel is obtained from the > kernel_module struct instead of directly. Which is a problem as > gcc-2.7.2 (perhaps others too) now munges the loading of the struct > (it miscalculates the offsets), and voila - you have no exception table. > > BTW, while looking at the new WP code, I noticed the "jmp 1f; 1:" > before and after are now gone - the comment above them (which lives on) > indicated they were Deep Magic(tm) to avoid some dark and mysterious > CPU bugs. I take it that science has prevailed over magic? ;-) The call/ret pair should have the same effect. -- Brian Gerst - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/