Messages in this thread | | | Date | Thu, 4 Sep 2008 21:23:01 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [PATCH RFC] x86: check for and defend against BIOS memory corruption |
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On Thu, 4 Sep 2008, Rafał Miłecki wrote: > > 2008/8/29 Rafał Miłecki <zajec5@gmail.com>: > > 2008/8/29 Hugh Dickins <hugh@veritas.com>: > >> Here's my version of Jeremy's patch, that I've now tested on my machines, > >> as x86_32 and as x86_64. It addresses none of the points Alan Cox made, > >> and it stays silent for me, even after suspend+resume, unless I actually > >> introduce corruption myself. Omits Jeremy's check in fault.c, but does > >> a check every minute, so should soon detect Rafał's HDMI corruption > >> without any need to suspend+resume. > > > > Your periodic test works fine: > > > > Corrupted low memory at ffff88000000be9c (be9c phys) = b02a0004 > > <IRQ> [<ffffffff8020fc9b>] check_for_bios_corruption+0x93/0x9f > > [<ffffffff8020fca7>] ? periodic_check_for_corruption+0x0/0x25 > > [<ffffffff8020fcb0>] periodic_check_for_corruption+0x9/0x25 > > > > By the way I confirmed this bug on Sony Vaio FW11M (my one is FW11S). > > Probably more machines from FW11* are affected. > > If this patch is known to work fine for Sony Vaio FW* and Alan's > machine, could it go mainline somehow?
Well.
Thanks for the prod, and I'm certainly remiss for not following up sooner. But I'm really not at all keen on such a patch going into mainline myself.
It's an interesting experiment, and I'd be happy to see such a patch (adjusted to make sure output goes to kerneloops.org) spending a little while in Fedora Rawhide (who'd be the right contact for that?).
But so far as mainline goes, I share Alan Cox's opinion that we should not be chopping pages out of every x86 user's memory, just because a couple of machines with faulty BIOSes have been observed.
Particularly now it's evident that the 64kB "limit" is no more than a reflection of where the directmap pagetable changes have caught such corruption.
If lots more such corruptions are reported, of course I would change my position; but those bad directmap PMD crashes are themselves quite recognizable now we know to look out for them.
I would prefer you both to use the minimal memmap= solutions for now; but others may disagree.
Hugh | |