| 摘要 |
A computer system includes a plurality of privileged commands, a global descriptor table, a section object, a callgate-creating module and a user program. The privileged commands is capable of communicating with a peripheral device connected to the computer system. The global descriptor table includes a spare descriptor that can be accessed by any user program having no privilege of directly calling the privileged commands. The section object is used for reading information from and writing information into the global descriptor table. The callgate-creating module is used for using the section object to create a callgate in the spare descriptor. The callgate indicates an entry of at least one of the privileged command. The user program having no privilege of directly calling the privileged commands can access the spare descriptor to call for said at least one privileged command via the callgate to communicate with the peripheral device.
|
