打开anaconda源码目录下的/docs/command-line.txt，其中有这么一句话：
updates         Prompt for floppy containing updates (bug fixes).
那么在bug fix当中，每次都去制作iso，不仅浪费时间，而且效果欠佳。最后就是越做越烦。那么有了这么一个工具，确实减轻了bug fix的繁琐。然后去anaconda的网站上查找得到如下资料（地址是http://fedoraproject.org/wiki/Anaconda/Updates）：

Anaconda Updates

anaconda has the capability to incorporate updates at runtime to fix any bugs or issues with the installer. These updates are generally distributed as a disk image file (referred to as updates.img from here on out). The updates.img can be used in a few different ways.

Updates types

There are a number of sources for the updates.

Updates from a disk image

The most common way of using an updates.img is to put it on a block device (either a floppy or a USB key). For a floppy drive, insert your floppy and then run

 dd if=updates.img of=/dev/fd0 bs=72k count=20

to put the contents of the image on your floppy. Then, boot the installer with

 linux updates

and you will be prompted to provide the location of your update disk.

You can also use a USB key or flash media -- just replace /dev/fd0 with the device that your USB key is at.

Updates from the Tree

If you're doing a network installation, you can also put the updates.img in your tree to be picked up by all installs from that tree. For Fedora Core 6 and later, put the file as images/updates.img in your Fedora installation tree. Earlier releases look in Fedora/base/updates.img.

Updates from the Network

If you're doing a network install and cannot modify your installation tree, you can place an updates.img in another location and boot with

 linux updates=http://some.website.com/path/to/updates.img

to load the updates.img from a remote web server.

If you have multiple network interfaces, anaconda will first prompt you to select one (unless you have used the ksdevice= boot parameter). It will then attempt to configure this link using DHCP. If you require other networking configuration, you will need to use various options. ksdevice= can be used to specify a different network device, and the ip= option (along with others for gateway, nameserver, and so forth) can be used for static configuration. All anaconda config options are described elsewhere .

How to Create an Anaconda Updates Image

If you are working on anaconda or looking at a bug and want to test your own bug fixes, it's easy to create your own updates.img file. There are two formats for the updates.img file. The first, and most common, is a gzip-compressed ext2 filesystem. The second is a gzip-compressed cpio archive.

Just do the following steps.

Compressed ext2 filesystem image

This is the more traditional form of an updates.img and is required for older releases of anaconda. It is also slightly more preferred if you are going to transfer the updates image to a floppy disk. Note that this requires root privileges.

1. Create a 1.44MB updates.img image

   dd if=/dev/zero of=updates.img bs=1k count=1440

2. Format as an ext2 filesystem

   mke2fs updates.img 

3. Mount the image

   mount -o loop updates.img /mnt 

4. Drop updated anaconda python files in a flat directory structure
5. Unmount the updates.img

   umount /mnt

Compressed cpio archive

This is the newer form of an updates.img and is likely preferred in most cases with current releases of anaconda. In contrast to the above, this does not require root privileges.

• Drop updated anaconda files in a flat directory structure, eg: /tmp/updates

   (cd /tmp/updates ; find -type f | cpio -c -o) | gzip -c9 > updates.img 

How to Examine an Anaconda Updates Image

updates.img files provided by the Fedora project are ext3 filesystem images. To examine one of these files complete the following steps:

1. Obtain an updates.image:

    wget http://people.redhat.com/~katzj/updates-f7t2.img

2. Mount the file using looopback:

   mount -o loop updates-f7t2.img /misc

To examine a cpio updates.img complete the following steps:

1. create a top level directory to hold the updates.img contents:

    mkdir /tmp/updates

2. unpack the updates into the directory:

    zcat updates.img | (cd /tmp/updates ; cpio -ivd) 

本人没有测试其cpio的，仅是简单的制作了一张虚拟软盘，然后用虚拟机虚拟软盘镜像。