The experimental status of the ICH9 chipset emulation should be documented

[Laurent Blume]

The documentation (quoted below) gives a rather positive view of the ICH9 chipset emulation, and its «experimental» status is easy to miss as it only appears in non-highlighted, size 6 font when hovering the mouse at exactly the right place. Updating the documentation to reflect that would allow for RTFM rather than RTFsmallprint answers when an update breaks it behavior.

Chipset

Here you can select which chipset will be presented to the virtual machine. Before VirtualBox 4.0, PIIX3 was the only available option here. For modern guest operating systems such as Mac OS X server, that old chipset is no longer well supported. As a result, VirtualBox 4.0 introduced an emulation of the more modern ICH9 chipset, which supports PCI express, three PCI buses, PCI-to-PCI bridges and Message Signalled Interrupts (MSI). This allows modern operating systems to address more PCI devices and no longer requires IRQ sharing.

[Frank Mehnert]

This was added a while ago, see the user manual section 14.1.