Date: Mon, 08 Mar 1999 17:49:47 -0800 From: Mike Smith <mike@smith.net.au> To: David Dawes <dawes@rf900.physics.usyd.edu.au> Cc: hackers@freebsd.org Subject: Re: Setting MTRRs from the X server Message-ID: <199903090149.RAA02067@dingo.cdrom.com> In-Reply-To: Your message of "Sun, 07 Mar 1999 15:33:50 %2B1100." <19990307153350.P4858@rf900.physics.usyd.edu.au>
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> For XFree86 4.0, we really need to be able to have the X server request > specific MTRR settings for different parts of a video card's physical > memory address space. While turning WC on for the framebuffer is a big > performance boost, a more critical issue is being able to make sure that > WC is turned off for areas that are used for memory mapped I/O. We've > found that some BIOSs enable WC in areas that our drivers want to use > for MMIO. One example is the 0xb0000-0xbffff range. > > So what I'm looking for is an interface that our X server can use to > request MTRR settings. An interface for this is present in the Linux > 2.2.x kernel (and we recently added code to use it), although it doesn't > currently allow changing the settings for the low 1MB of address space > (but I'm told that will be added at some point). For want of anything better, I'd guess that emulating the Linux interface would probably be the way to go. Is there a spec for it somewhere that can be read? -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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