Both companies, in announcing the changes this week, said that they hope to increase the number of Linux platforms that are compatible with their hardware.
"By making these source codes freely available, Via is expanding our software focus and enabling tailor-made solutions for the latest Linux distributions," Steve Charng, Via's head of software development, said in a statement.
Via released the source code of various drivers, including its S3 Graphics UniChrome family of drivers, which support the Via Epia motherboards. This family of drivers is likely to be of particular interest to Linux enthusiasts, according to the company, because it supports the Linux 2.6.x kernel.
The company has also released the driver source code for its Via ProSavage and ProSavage DDR integrated graphics controllers.
XGI released the driver source code for a number of its products, including XGI Volari V5, V8 and Z7.
It can sometimes be difficult to run Linux on certain hardware, as many drivers are designed to work with Microsoft Windows or Mac OS X.
Although chip vendors such as Intel and ATI Technologies support Linux, they only offer graphics drivers for two of the major commercial Linux distributions, Red Hat and SuSE, according to the Intel and ATI Web sites.
Via and XGI's decision to release the source code of various drivers should make it easier for Linux users to find drivers for the hardware they buy, although the chipmakers are relying on the goodwill of the open-source community to write drivers.
Ingrid Marson of ZDNet UK reported from London.