Malformed fonts in Firefox

[YZMSQ]

Hi,
My box runs on a Intel Sandy bridge chip, and previously I've updated my xorg and any related ports to the latest one in experimental xorg repo via svn (with KMS enabled). However, there are some malformed fonts shown in the Firefox (including firefox-esr and linux-firefox) unexpectedly sometimes, as shown in the following picture, and I couldn't figured it out currently. However, the fonts are really normal in other browsers, say, Opera and Chromium. So, what should I do to deal with it? Thank you.:e

Malformed fonts in Firefox:

What I've installed:

justin@darkgeek.pts/1 ~ % uname -a
FreeBSD darkgeek 9.1-RELEASE FreeBSD 9.1-RELEASE #0 r243826: Tue Dec  4 06:55:39 UTC 2012     root@obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
 
justin@darkgeek.pts/1 ~ % ident /usr/ports/www/firefox/Makefile
/usr/ports/www/firefox/Makefile:
      $FreeBSD: www/firefox/Makefile 313676 2013-03-08 22:27:39Z flo $
 
justin@darkgeek.pts/1 ~ % pkg info | grep xorg
linux-f10-xorg-libs-7.4_1      Xorg libraries (Linux Fedora 10)
xorg-fonts-truetype-7.7        X.Org TrueType fonts
xorg-minimal-7.5.2             X.Org minimal distribution metaport
xorg-server-1.12.4,1           X.Org X server and related programs

justin@darkgeek.pts/1 ~ % pkg info | grep libdrm
libdrm-2.4.42_1                Userspace interface to kernel Direct Rendering Module services

justin@darkgeek.pts/1 ~ % pkg info | grep libGL
libGL-8.0.5_3                  OpenGL library that renders using GLX or DRI
libGLU-8.0.5                   OpenGL utility library

justin@darkgeek.pts/1 ~ % pkg info | grep intel
xf86-video-intel-2.21.5        Driver for Intel integrated graphics chipsets

 

[YZMSQ]

Well, since xf86-video-intel-2.21.5 in xorg-dev has supported SNA, so I tried to enable SNA by adding this line to my xorg.conf:

Option      "AccelMethod" "sna"

However, I think this has led me to that issue I posted before. After disabling this option, the fonts in Firefox become normal.