Messages in this thread | | | Date | Sun, 13 Apr 2014 18:09:24 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH 1/3] x86: microcode: report if CPU has up-to-date microcode |
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On Mon, Mar 31, 2014 at 07:08:08PM +0200, Denys Vlasenko wrote: > What prompted me to create this patch is a bunch of vmcores > from people having mysterious crashes. > > Basically, I am in a real-world scenario where I have only vmcore > from somebody else. I have no /proc/cpuinfo. > > Every bit of information I don't have at a minimum incurs email > round-trip delay. > > Eventually I did manage to figure out what version of microcode > my users had (they did have old one), but it took some time.
Out of curiosity: the old microcode version wasn't the culprit for the bug, was it?
> You are correct, the lack of boot-time dmesg is a problem for > post-mortem vmcore analysis in general. > > I contemplate creating a patch to optionally save it.
Btw, can vmcore stash ucode version somewhere too, as part of the data dump it saves? Or even the whole /proc/cpuinfo?
> That is not a bad thing: if my users would have been spooked that > way, maybe they'd install a newer microcode. Or newer BIOS with new > microcode - they did not do that either, despite it being available > from the manufacturer for two years already.
Right, ok. So in thinking about this more. How about we drop the "bool report_old" machinery and add those printks as debug printks? And by that I mean,
printk(KERN_DEBUG...
and not all that other pr_debug() gunk?
This way, you need to boot with "debug" or "ignore_loglevel" on the cmdline and they will get issued.
My concern is still with spooked users who'll come and say, my machine says:
+ pr_info("microcode: CPU rev 0x%x is same or newer" + " than 0x%x in microcode data\n",
Does that mean, I need to go and replace my CPU?
The usual case is that microcode gets upgraded with system upgrade as a intel-ucode or amd-ucode or whatever package, so people upgrading their distros will always get the latest ucode anyway.
Hmmm.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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