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A recently discovered bug can "freeze up" computers using Cyrix 6x86 series processors, similar to the manner in which the Pentium "F0" bug works, according to German computer magazine C't.
The Pentium "F0" bug, first reported by CNET's NEWS.COM last Friday, is an illegal instruction from a program that can freeze up Pentium MMX and "classic" Pentium (non-MMX) computers and prevent further communication between a program and processor.
The consequence of the Cyrix bug is the same--any multiuser system with the affected processors will shut down--but the series of instructions are different, according to observers who have studied the problem.
"The fact that one program in a multiprogramming environment can do something that adversely affects other programs is clearly a problem," says Nathan Brookwood, an analyst with market research firm Dataquest.
However, the possibility that a vast number of Cyrix or Pentium systems will be affected by the two bugs is small, Brookwood said. "I doubt that many Cyrix processors, or even many Pentium processors, at this point, are deployed in these multiuser configurations." Even where those processors are used in systems with multiple users, connected systems aren't vulnerable to the bug unless someone deliberately runs a program containing the illegal instructions, he said.
At least one Web site is claiming that the Cyrix bug can be prevented simply with a series of commands that make the processor ignore the illegal commands.
Cyrix yesterday acknowledged the existence of the bug, but says it is a much less severe problem than the Pentium "F0" bug. There is a series of legal instructions that can be put into an illegal sequence that causes the system to freeze, according to a company spokesperson.
"For the average person using off-the-shelf software, you won't run into this problem at all. For developers, the majority of compilers won't let you put together code [in this fashion]," the spokesperson said.
Cyrix said it would post a fix by the end of yesterday on its Web site.
