diff options
| author | Keith Packard <keithp@keithp.com> | 2008-04-17 10:04:55 -0700 |
|---|---|---|
| committer | Zhenyu Wang <zhenyu.z.wang@intel.com> | 2008-04-21 15:06:47 +0800 |
| commit | f08aa4c291e4f5491372434e3ee08dfb15d5aa94 (patch) | |
| tree | b507c012a0a26e93a2235c5aa502f4e712eadeda | |
| parent | 8187a5a16f8bd8f0ba5e7f5357f355928b3b8f07 (diff) | |
Add a kludge-around to fix cd/wt bits in fb ptes on linux.
Mmap from /sys/devices/pci* on linux forces the cache-disable and
write-through bits, which turns our write-combining map into an
uncached-map, seriously impacting performance. It turns out that a bug in
mprotect allows us to fix this by disabling access to those pages and then
immediately re-enabling them.
(cherry picked from commit c3fb62df4e60b63295f94c99b3c5de70dbf94e1c)
| -rw-r--r-- | configure.ac | 3 | ||||
| -rw-r--r-- | src/i830_driver.c | 10 |
2 files changed, 13 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 170d59b4..001e5e16 100644 --- a/configure.ac +++ b/configure.ac @@ -43,6 +43,9 @@ AM_PROG_CC_C_O AC_CHECK_PROG(gen4asm, [intel-gen4asm], yes, no) AM_CONDITIONAL(HAVE_GEN4ASM, test x$gen4asm = xyes) +AC_CHECK_HEADERS(sys/mman.h) +AC_CHECK_FUNCS(mprotect) + AH_TOP([#include "xorg-server.h"]) AC_ARG_WITH(xorg-module-dir, diff --git a/src/i830_driver.c b/src/i830_driver.c index 41c0578a..f4046779 100644 --- a/src/i830_driver.c +++ b/src/i830_driver.c @@ -197,6 +197,9 @@ USE OR OTHER DEALINGS IN THE SOFTWARE. #include "i830_debug.h" #include "i830_bios.h" #include "i830_video.h" +#if HAVE_SYS_MMAN_H && HAVE_MPROTECT +#include <sys/mman.h> +#endif #ifdef INTEL_XVMC #define _INTEL_XVMC_SERVER_ @@ -685,6 +688,13 @@ I830MapMem(ScrnInfoPtr pScrn) err = pci_device_map_range (device, pI830->LinearAddr, pI830->FbMapSize, PCI_DEV_MAP_FLAG_WRITABLE | PCI_DEV_MAP_FLAG_WRITE_COMBINE, (void **) &pI830->FbBase); + if (err) + return FALSE; + /* KLUDGE ALERT -- rewrite the PTEs to turn off the CD and WT bits */ +#if HAVE_MPROTECT + mprotect (pI830->FbBase, pI830->FbMapSize, PROT_NONE); + mprotect (pI830->FbBase, pI830->FbMapSize, PROT_READ|PROT_WRITE); +#endif #else pI830->FbBase = xf86MapPciMem(pScrn->scrnIndex, VIDMEM_FRAMEBUFFER, pI830->PciTag, |