The screen size is limited by VIA chipsets' ability. The supported VIA chipsets are listed in Appendix A. Supported VIA Chipsets. This section introduces the screen size limitation of most commonly used VIA chipsets.

Hardware Capability

The pitch is how many bytes in the linear frame buffer there are between one pixel's data, and the data of the pixel immediately below. You can think of this as the horizontal resolution multiplied by the bytes per pixel (bits per pixel divided by 8). In practice, the pitch may be more than this product because video hardware often has requirements that the pitch be a multiple of some value.

MAX Virtual Screen Size

When using the XRandR extension:
      MAX Virtual Screen Width = min (MAX Screen Width on IGA1, MAX Screen Width on IGA2)
In order to make rotation easy, it is recommended to set the virtual size square.

When not using the XRandR extension, the maximum virtual screen size is limited to 3840 * 2880.

The numbers in the table above reflect hardwares' ability. However, due to the 32-byte alignment of pitch, the MAX size setting in xorg.conf is not exactly the same. Take VX855 for example, the MAX pitch is alignDown_32byte(2¹⁴-1) = 16352, and
      MAX screen width = MAX pitch /(depth/8)
When depth is 32 bpp, the max screen size should be 4088.

Texture Pitch and MAX Texture Width

The texture pitch of CN700/CX700 can be set by registers.

For CN896/VX800/VX855 chipsets,
       Texture pitch = MAX(texture width) * (Depth of indicated texture)/8
The MAX texture pitch is the result when the depth is 32.

The texture pitch limitation is for programming reference.