On Tue, 2007-11-13 at 15:15 +0100, Andi Kleen wrote: > Max Asbock <[EMAIL PROTECTED]> writes: > > > Now that the 32-bit and 64-bit x86 machine check handlers live next to > > each other a certain asymmetry in functionality is apparent. Notably, > > the 64-bit machine check handler implements a timer that periodically > > polls for silent machine check errors and makes them accessible to user > > space through /dev/mcelog. > > Actually 32bit implements that too (non-fatal.c). But it misses some > of the more advanced functionality like AMD Threshold Interrupts. > > > Are there reasons the x86 32-bit machine > > check handler couldn't do the same? > > The 32bit machine check code has some serious design problems. The > best would be probably to just move 32bit over to the 64bit code too. In > fact there was a patch to do that some time ago, but it ran into some > minor problems and was unfortunately never merged. But it would be the > right thing to do.
I found patch from about three years ago that implemented a 32-bit version of the x86_64 machine check handler. Do you know of any newer attempts? However, given the merge of x86, a single implementation should be able to handle both the 32-bit and 64-bit cases. I tried to build the 64-bit machine check handler (mce_64.c) for 32-bit to see what kind problems it would run into. So far I found a few things: - there is no idle_notifier_register in 32-bit x86 - there is no oops_begin in 32-bit x86 - register names are different (rip, cs) - some data types would have to adjusted to be 64 bit The issues seem to be surmountable. > The only missing functionality on the 64bit side would be support for > old non IA compliant old machine checks like P5 or WinChip. One option > would be to simply drop them. AFAIK these CPUs don't really have > anywhere near usable machine check capability anyways so dropping it > would not make much difference. Or alternatively keep p5.c/winchip.c > around. But if you look at them they don't do much except simple > printk with not much information and printk in a machine check handler > is always wrong because it can deadlock. I personally would prefer > dropping. > > And I think one or two K7 quirks are also missing on 64bit, but these > would be very easy to add. Other than that it should just work on > 32bit CPUs. > So it looks like giving 32-bit x86 the same machine check support as in 64-bit is both feasible and desirable. Are there any plans to do this or is anybody currently working on it? thanks, Max - 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/
