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Date: Mon, 26 Oct 2009 21:11:54 +0100 From: Dmitry Adamushko <dmitry.adamushko@...il.com> To: Mike Travis <travis@....com> Cc: Ingo Molnar <mingo@...e.hu>, Tigran Aivazian <tigran@...azian.fsnet.co.uk>, Thomas Gleixner <tglx@...utronix.de>, Andrew Morton <akpm@...ux-foundation.org>, Jack Steiner <steiner@....com>, "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org, Andreas Mohr <andi@...as.de>, Hugh Dickins <hugh@...itas.com>, Hannes Eder <hannes@...neseder.net>, linux-kernel@...r.kernel.org Subject: Re: [PATCH 6/8] SGI x86_64 UV: Limit the number of microcode messages 2009/10/26 Mike Travis <travis@....com>: > > > Ingo Molnar wrote: >> >> * Dmitry Adamushko <dmitry.adamushko@...il.com> wrote: >> >>> 2009/10/24 Tigran Aivazian <tigran@...azian.fsnet.co.uk>: >>>> >>>> On Sat, 24 Oct 2009, Dmitry Adamushko wrote: >>>>>> >>>>>> - printk(KERN_INFO "microcode: CPU%d sig=0x%x, pf=0x%x, >>>>>> revision=0x%x\n", >>>>>> + if (cpu_num < 4 || !limit_console_output(false)) >>>>>> + printk(KERN_INFO >>>>>> + "microcode: CPU%d sig=0x%x, pf=0x%x, >>>>>> revision=0x%x\n", >>>>>> cpu_num, csig->sig, csig->pf, csig->rev); >>>>>> >>>>> Hmm, I guess we wouldn't lose a lot by simply removing those messages >>>>> completely. Per-cpu pf/revision is available via /sys anyway. >>>> >>>> The reason for printing them is that the pf (possibly others?) can >>>> change by the update and so the log has this info handy. >>> >>> We might store the old sig/pf/revision set as well, export them via >>> /sys or/and print them at update-to-new-microcode time. >>> >>> If it's really so useful to have this info in the log and, at the same >>> time, to avoid the flood of messages (which, I guess for the majority >>> of systems, are the same) at startup time, we might delay the printout >>> until the end of microcode_init(). Then do something like this: >>> >>> microcode cpu0: up to date version sig, pf, rev // let's say, >>> it was updated by BIOS >>> microcode cpus [1 ... 16] : update from sig, pf, rev to sig, pf2, rev2. >>> >>> Anyway, my humble opinion, is that (at the very least) the current >>> patch should be accompanied by a similar version for amd. >> >> yeah. Since we load new microcode on all cpus it's enough to print it for >> the boot CPU or so. >> >> Having the precise microcode version printed (or exposed somewhere in >> /sys) is useful - sometimes when there's a weird crash in some prototype CPU >> one of the first questions from hw vendors is 'which precise microcode >> version was that?'. >> >> Ingo > > I would agree especially in the case where not all the cpus are exactly > the same. But so far, I've only seen variations of the speed of the cpus > not it's generic type, in an SSI. So the version of the microcode was > identical in all cases. I guess that (at least) a bootup cpu can be updated by BIOS so that it may appear to be different. Perhaps, cases where some 'broken' cpus have been replaced for others with a different "revision" (but still compatible otherwise) might be rare but possible (say, big machines with hot-pluggable cpus) ? btw., I was thinking of having something like this: microcode: cpus [K...L] platform-specific-format (e.g. for Intel : sig, pf, rev) microcode: updating... microcode: cpus [K...L] platform-specific-format (e.g. for Intel : sig, pf, rev) or even just, microcode: cpus [ K...L] updated from platform-specific-format-1 to platform-specific-format-2 > > Thanks, > Mike > -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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