> -----Original Message----- > From: Marc Jones [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 17, 2008 4:28 PM > To: Myles Watson > Cc: 'Coreboot' > Subject: Re: [coreboot] HT credits and the Opteron > > Myles Watson wrote: > > Anyone with detailed knowledge of (or more manuals than I have for) the > > Opteron, > > > > I just noticed that the Nvidia ck804 reduces the amount of credits which > the > > Opteron gives it (probably due to an errata.) Does that mean that there > > should be more credits available for the other HT links? Is buffer > space > > per link or does the CPU share it all between all the links? What if a > link > > is disabled? Should you give its credits to the others? > > > > In the BKDG for the Opteron it says that you shouldn't change the values > in > > general, because software picks the right values, but that's us. It > doesn't > > say how you should pick new values. > > > > > Myles,
Marc, Thanks for the quick response. > I assume that you are talking about the XBAR buffer allocation, 4.6.12? Sorry. I should have been more clear. I was talking about 3.3.15: LDTi Buffer Count Registers. Does your answer still apply? > The links are profiled by the designers and then appropriate values are > assigned. There are some limitations in allocating the buffers so you > can't just take some form one place an use it somewhere else. For the > most part, you shouldn't run out of buffers in a typical system, so > nothing would be gained by adding more to a particular interface. > > Generally, we should set what the factory bios sets since those settings > are validated. If a customer is building their own platforms we will > work with them to set appropriate values for their silicon. Now that there is an open-source HT core from the University of Mannheim, anyone could do this, but maybe most people will leave it alone. Thanks, Myles -- coreboot mailing list [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
