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Hi all,
I am using Linux ubuntu Operating system. Its Radeon KMS code merged to Linux 2.6.31, but now it has formally completed the process, Intel and ATI's support has been a comprehensive KMS. Then on the other supports nVIDIA's KMS, it will achieve by the Nouveau project may occur in the linux 2.6.32 or 2.6.33. So far, Fedora 11 has support for ATI KM. Please reply some feature of KMS (Kernel Mode-Setting) support. Thanks in advance.
KMS (Kernel Mode-Setting) means the kernel mode setting: in the kernel initialization, and also completed before the beginning of graphics, so that the display device to load from grub into the desktop, use the standard resolution, do not need frequent switching mode. All the best.
The CPU is the current X86 permission to provide four different modes: The actual operating system generally use only two: the user mode (Ring3) and kernel mode (Ring0). Non-privileged user mode model can not directly manipulate memory and hardware. Application to use the hardware, the kernel through system calls using the provided interface. Linux, most of the drive is directly into the kernel, use kernel mode (Kernel Mode). Display driver is an exception, run in user mode (User Mode). The advantage of user mode and kernel-driven development can be decoupled. In the past, most graphics card manufacturers to develop their own independence when the drive is an option of last resort. The disadvantage is that the interaction interface, the kernel is rather complicated, large amounts of data between the kernel and user pass, X must have Root privileges, the kernel can not completely control equipment, can not power management. All the best.
Kernel mode setting is not a simple code to move. In addition to the various clean-up call interface, the memory management is also a large. TTM is committed to work in this area, but the API has encountered a little problem. So was Intel abandoned the use of unified memory management system in favor of development of GEM. Intel GEM for their hardware design, development relatively easy. So Intel's most advanced kernel mode setting, the basic development of the current function has been completed, including power management. So the latest development tree XServer have deleted the original user mode setting code. All the best.
AMD / ATI a little bit slow progress, as compared to Intel's integrated graphics, ATI needs to support the chip is a lot more functions are complex. GEM can not meet the ATI graphics card and memory management requirements, ATI chose to continue improving the TTM. Recently, TTM has also been integrated into the kernel, it has no major obstacle to progress. Kernel mode is set now has support R100 ~ R700, R800 will soon join the support. KMS is also present in the Staging tree, is expected to soon graduated from the Staging. Power Management support has not joined, so my books in Linux, significantly higher than the thermal Windows 7. In the 2.6.34 kernel is expected to join the power management support. Check and reply.
KMS have many functios like:
# Kernel mode setting means moving the mode setting functionality from video drivers from the userspace X drivers into the kernel.
# Kernel mode setting means moving mode setting from the kernel to user space X driver video driver functions. While this may seem arbitrary and uninteresting for end-users, this isn't exactly the case.
# Although it may seem arbitrary, and ultimately uninteresting user, this is not the case.
# Kernel mode setting enables a much richer boot experience, less problems with sleep / wake cycles, and improved VT switching.