Date: Wed, 16 Sep 2015 06:59:04 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: Dieter BSD <dieterbsd@gmail.com>, freebsd-hardware@FreeBSD.org, freebsd-hackers@FreeBSD.org Subject: Re: ECC support Message-ID: <20150916035904.GE67105@kib.kiev.ua> In-Reply-To: <55F88A18.6090504@FreeBSD.org> References: <CAA3ZYrBXZn1WpHWYGJYWJDPsk7iDahCas8RhnHC4w%2Babf4w4hA@mail.gmail.com> <55F88A18.6090504@FreeBSD.org>
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On Wed, Sep 16, 2015 at 12:14:00AM +0300, Andriy Gapon wrote: > On 15/09/2015 23:53, Dieter BSD wrote: > > Assuming that a board does have the necessary connections but > > the firmware does not have ECC support, is there some reason that > > ECC support could not be added to the OS instead of the firmware? > > Yes, there is. The memory controller is programmed by the code that runs from > ROM and uses no RAM (or the CPU cache is used as the RAM). Once the real RAM > gets used it's too late to reprogram the DRAM controller. This is true at least > for most or all of the modern day x86 hardware. For modern Intel hardware, the IMC config is locked before BIOS passes the control to the user code, i.e. OS loader. It does not help much that the documentation for IMC is not provided even under NDA.
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