/*不可修改的屏幕信息，用户空间可见*/
struct fb_fix_screeninfo {
char id[16]; /* identification string eg "TT Builtin" */
unsigned long smem_start; /* Start of frame buffer mem 显存的起始地址*/
/* (physical address) */
__u32 smem_len; /* Length of frame buffer mem 显存的大小 */
__u32 type; /* see FB_TYPE_* */
__u32 type_aux; /* Interleave for interleaved Planes */
__u32 visual; /* see FB_VISUAL_* */
__u16 xpanstep; /* zero if no hardware panning */
__u16 ypanstep; /* zero if no hardware panning */
__u16 ywrapstep; /* zero if no hardware ywrap */
__u32 line_length; /* length of a line in bytes 每行的字节数 */
unsigned long mmio_start; /* Start of Memory Mapped I/O */
/* (physical address) */
__u32 mmio_len; /* Length of Memory Mapped I/O */
__u32 accel; /* Type of acceleration available */
__u16 reserved[3]; /* Reserved for future compatibility */
};
/* Interpretation of offset for color fields: All offsets are from the right,
* inside a "pixel" value, which is exactly 'bits_per_pixel' wide (means: you
* can use the offset as right argument to
* stream and is written to video memory as that unmodified. This implies
* big-endian byte order if bits_per_pixel is greater than 8.
*/
/*像素所占字节内，各个颜色的位分配比如RGB=888,565,555等等，*/
struct fb_bitfield {
__u32 offset; /* beginning of bitfield */
__u32 length; /* length of bitfield */
__u32 msb_right; /* != 0 : Most significant bit is */
/* right */
};
