From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 27 Aug 1999 15:09:41 +0200 (CET) From: Marc Dietrich To: linuxppc-dev@lists.linuxppc.org Subject: Re: bug in l2cr status display? Message-Id: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Hello out there, I've downloaded the 750 PDF Manuel and to Bit #9 (L2DO) it says: "L2 Data-only. Setting this bit enables data-only operation in the L2 cache..." ^^^^ So setting this bit disables instruction caching therefore it should'nt be set on bootup. It seems to me, that the L2CR programming is implemented but disabled in current kernel version. The L2CR=xxxxxxx doesn't work for me. By the way, it seems that Motola (or IBM) uses different cache chips on the 750 CPU - one with 0.5 and one with 1.0 ns timings. 0.5 ns are the common used chips while mine has a 1.0ns timing. This causes the PowerLogix Cache Control to crash my Mac. Has anyone expiriances on this? How has this been to recocnice in the kernel boot-up? Marc On Thu, 26 Aug 1999, Michel Lanners wrote: > > Hi all, > > While playing with the l2cr in order to set it manually after OF > booting, I've come across the following. > > It seems that the effect of the L2CR[DO] bit isn't clear. In the 750 > user manual, in the table describing l2cr, it says '... setting this > bit enables the caching of instructions'. This doesn't corrsspond to > the name of the register, nor to what I see with my G3 upgrade card: in > normal operation, L2CR[DO] isn't set, but it makes no sense to disable > instruction caching excpet for test purposes. > > So, what's happening? Is the user manual wrong? In that case, we should > correct arch/ppc/kernel/ppc_htab.c accordingly. > > Any Motorola engineer around? Others with better docs? FWIW, I checked > the 750 errata already... nothing. > > Michel [[ This message was sent via the linuxppc-dev mailing list. Replies are ]] [[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]] [[ reply is of general interest. Please check http://lists.linuxppc.org/ ]] [[ and http://www.linuxppc.org/ for useful information before posting. ]]