自打装好Fedora 12之后就发现chromium不能用rpm安装了，安装时总是缺这少那，很是费劲，于是按照网上的方法，在/etc/yum.repos.d/下创建一个chromium.repo，内容如下：
[chromium] name=Chromium Test Packages baseurl=http://spot.fedorapeople.org/chromium/F$releasever/ enabled=0 gpgcheck=0
然后通过yum安装就可以了。
今天在Fedora People看到有新的chromium安装包出现，于是打算升级chromium。下载了所有的rpm包(忘记了最初是通过yum安装的)。安装时chromium, chromium-libs都能通过rpm -Uvh正常安装，可是升级v8时还是出了问题。想起以前的教训，打算先把v8完全卸载再安装，可是缺无法卸载，无论是通过rpm -e还是yum remove都不行。
这时想到了用yum upodate v8-*，结果却出现了“Package v8-devel-2.0.3-1.20091209svn3443.fc12.i686.rpm is not signed”的错误。在网上找到一个办法，就是编辑 /etc/yum.conf
，把gpgcheck=1 改为 gpgcheck=0。不过这样做有潜在的风险，因此在安装完v8之后就立刻把gpgcheck重新设为1.
另外一个奇怪的问题是，打开Chromium时，浏览器打不开，而且SELinux总是报错：
Summary:
SELinux is preventing /usr/lib/chromium-browser/chromium-browser from loading
/usr/lib/chromium-browser/libmedia.so which requires text relocation.
Detailed Description:
The chromium-browse application attempted to load
/usr/lib/chromium-browser/libmedia.so which requires text relocation. This is a
potential security problem. Most libraries do not need this permission.
Libraries are sometimes coded incorrectly and request this permission. The
SELinux Memory Protection Tests
(http://people.redhat.com/drepper/selinux-mem.html) web page explains how to
remove this requirement. You can configure SELinux temporarily to allow
/usr/lib/chromium-browser/libmedia.so to use relocation as a workaround, until
the library is fixed. Please file a bug report.
Allowing Access:
If you trust /usr/lib/chromium-browser/libmedia.so to run correctly, you can
change the file context to textrel_shlib_t. "chcon -t textrel_shlib_t
'/usr/lib/chromium-browser/libmedia.so'" You must also change the default file
context files on the system in order to preserve them even on a full relabel.
"semanage fcontext -a -t textrel_shlib_t
'/usr/lib/chromium-browser/libmedia.so'"
Fix Command:
chcon -t textrel_shlib_t '/usr/lib/chromium-browser/libmedia.so'
Additional Information:
Source Context unconfined_u:unconfined_r:unconfined_execmem_t:s0-
s0:c0.c1023
Target Context system_u:object_r:lib_t:s0
Target Objects /usr/lib/chromium-browser/libmedia.so [ file ]
Source chromium-browse
Source Path /usr/lib/chromium-browser/chromium-browser
Port <Unknown>
Host bonn.yang
Source RPM Packages chromium-4.0.273.0-0.1.20091216svn34775.fc12
Target RPM Packages chromium-libs-4.0.273.0-0.1.20091216svn34775.fc12
Policy RPM selinux-policy-3.6.32-56.fc12
Selinux Enabled True
Policy Type targeted
Enforcing Mode Enforcing
Plugin Name allow_execmod
Host Name bonn.yang
Platform Linux bonn.yang 2.6.31.6-166.fc12.i686.PAE #1 SMP
Wed Dec 9 11:00:30 EST 2009 i686 i686
Alert Count 11
First Seen Wed 23 Dec 2009 09:38:16 PM CST
Last Seen Wed 23 Dec 2009 10:28:36 PM CST
Local ID b1f55f28-145d-48dd-9d71-6fb7fe6a57c8
Line Numbers
Raw Audit Messages
node=bonn.yang type=AVC msg=audit(1261578516.240:27332): avc: denied { execmod } for pid=2946 comm="chromium-browse" path="/usr/lib/chromium-browser/libmedia.so" dev=sda2 ino=277322 scontext=unconfined_u:unconfined_r:unconfined_execmem_t:s0-s0:c0.c1023 tcontext=system_u:object_r:lib_t:s0 tclass=file
node=bonn.yang type=SYSCALL msg=audit(1261578516.240:27332): arch=40000003 syscall=125 success=no exit=-13 a0=8ff8000 a1=63000 a2=5 a3=bf899bf0 items=0 ppid=1 pid=2946 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 tty=(none) ses=1 comm="chromium-browse" exe="/usr/lib/chromium-browser/chromium-browser" subj=unconfined_u:unconfined_r:unconfined_execmem_t:s0-s0:c0.c1023 key=(null)
试了半天也没能在SELinux中设好libmedia.so的permission（有人说只要把libmedia.so的permission设为permissive就可以）。后来在一个法语的网页上(http://tuxmaya.wordpress.com/2009/12/21/nuevos-paquetes-de-chormium-en-fedora/
)发现了这样一条命令来取消 SELinux 对 /usr/lib/chromium-browser/下的所有.so文件的permission 的检查。
chcon -t texrel_shlib_t /usr/lib*/chromium-browser/*.so
另外，该网页(http://forums.fedoraforum.org/showthread.php?t=237029
)上也提到了这种方法。
设置之后，chromium就可以正常工作了。这篇博文就是用chromium来写的。
PS:
写完博文后在SELinux的错误信息中发现了fix的方法：
hcon -t textrel_shlib_t '/usr/lib/chromium-browser/libmedia.so'
semanage fcontext -a -t textrel_shlib_t '/usr/lib/chromium-browser/libmedia.so'
实在是太粗心了，当时竟然没有仔细看…… 谨记这一教训！