From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesse Barnes Subject: Re: [Bug #12608] 2.6.29-rc powerpc G5 Xorg legacy_mem regression Date: Sat, 7 Feb 2009 15:15:20 -0800 Message-ID: <200902071515.20560.jbarnes@virtuousgeek.org> References: <200902061445.11379.jbarnes@virtuousgeek.org> <1233975910.31963.56.camel@pasglop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1233975910.31963.56.camel@pasglop> Content-Disposition: inline Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Benjamin Herrenschmidt Cc: Hugh Dickins , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List On Friday, February 6, 2009 7:05 pm Benjamin Herrenschmidt wrote: > On Fri, 2009-02-06 at 14:45 -0800, Jesse Barnes wrote: > > + if (Base <= 1024*1024) { > > + /* Try legacy_mem (may not be available or implemented) */ > > + if ((fd = linuxOpenLegacy(dev, "legacy_mem")) < 0) { > > + addr = mmap(NULL, Size, PROT_READ|PROT_WRITE, MAP_SHARED, > > fd, Base); + close(fd); > > + if (addr && addr != MAP_FAILED) > > + return addr; > > + } > > } > > - return addr; > > + > > + /* Fall back to old method if legacy_mem fails or Base >= 1M */ > > + return linuxMapPci(ScreenNum, Flags, dev, Base, Size, > > PCIIOC_MMAP_IS_MEM); } > > I don't like the fallback if legacy_mem exists and returns an error, > that's an indication that legacy memory is -not- available and thus > whatever 'fallback' X will try (supposedly using /dev/mem) will be > horribly broken and will probably end up scribbling all over system > memory :-) Yeah, but unless we fix all the callers (and possibly their callers), not falling back will keep X from starting... -- Jesse Barnes, Intel Open Source Technology Center