启动EXA

什么是EXA？
EXA is a graphics acceleration architecture of the X.Org Server (see also X Window System) designed to replace XAA ^[1] (the XFree86 Acceleration Architecture) and to make the XRender extension more usable, with only minor changes needed to adapt XFree86 video drivers written to use XAA; it was designed by Zack Rusin and announced at LinuxTag 2005^[2] and first released with X.Org Server version 6.9/7.0.
EXA是X.Org Server的、被设计来替代XAA一种图形加速架构。它由Zack Rusin设计，在LinuxTag 2005大会上宣布，并随X.Org Server 6.9/7.0版本首次发布。
如何启用EXA？
修改/etc/X11/xorg.conf文件
在显卡的Device小节的最后添加一行：

   Option "AccelMethod" "exa"

（you will need at least

    Option "AccelMethod" "exa"

in your card's Device section in xorg.conf.）
如何查看EXA是否启用？
==============/var/log/Xorg.0.log without exa====================
(II) Loading sub module "vgahw"
(II) LoadModule: "vgahw"
(II) Loading /usr/lib/xorg/modules//libvgahw.so
(II) Module vgahw: vendor="X.Org Foundation"
compiled for 1.3.0, module version = 0.1.0
ABI class: X.Org Video Driver, version 1.2
(**) intel(0): Depth 24, (--) framebuffer bpp 32
(==) intel(0): RGB weight 888
(==) intel(0): Default visual is TrueColor
(II) intel(0): Integrated Graphics Chipset: Intel(R) 965GM
(--) intel(0): Chipset: "965GM"
(--) intel(0): Linear framebuffer at 0xD0000000
(--) intel(0): IO registers at addr 0xF4000000
(II) intel(0): 2 display pipes available.
(==) intel(0): Using XAA for acceleration
(--) intel(0): Will try to allocate texture pool for old Mesa 3D driver.
(II) intel(0): Will try to reserve 32768 kiB of AGP aperture space
for the DRM memory manager.
================================================================
==============/var/log/Xorg.0.log with enable exa====================
(II) Loading sub module "vgahw"
(II) LoadModule: "vgahw"
(II) Loading /usr/lib/xorg/modules//libvgahw.so
(II) Module vgahw: vendor="X.Org Foundation"
compiled for 1.3.0, module version = 0.1.0
ABI class: X.Org Video Driver, version 1.2
(**) intel(0): Depth 24, (--) framebuffer bpp 32
(==) intel(0): RGB weight 888
(==) intel(0): Default visual is TrueColor
(**) intel(0): Option "AccelMethod" "exa"
(II) intel(0): Integrated Graphics Chipset: Intel(R) 965GM
(--) intel(0): Chipset: "965GM"
(--) intel(0): Linear framebuffer at 0xD0000000
(--) intel(0): IO registers at addr 0xF4000000
(II) intel(0): 2 display pipes available.
(**) intel(0): Using EXA for acceleration
(--) intel(0): Will try to allocate texture pool for old Mesa 3D driver.
(II) intel(0): Will try to reserve 32768 kiB of AGP aperture space
for the DRM memory manager.
==========================================================================