Query about Linux framebuffer implementation

[胡杨树]

Hi, all

driver/video/fbmem.c implement framebuffer as a char device, in read/write API of this char device file operations, WHY does we need to: 
1st:kmalloc a space
2st:copy data between video memory buffer and kmalloced space above
3rd:copy kmalloced space data to/from user space buffer

why the hell we just copy data between video memory and user space buffer?


THX
ROCKY