the virtualbox-bin alsa conflict with other [solved]

virtualbox guest starts, no sound, but the system is another program using the alsa
all normal sound card to transfer the guest virtualbox oss or pulseaudio to drive, then the client virtualbox started, host of the program can not use all alsa.

add this line to /etc/portage/package.mask/custom:

add this line to /etc/portage/package.use/custom:
media-libs/libsdl -esd
emerge -aN media-libs/libsdl
After this sound will work in virtualbox.

(thanks as Yuriy Blokhin )

do edit gentoo for virtualbox because Multiple vulnerabilities were found in VirtualBox, allowing local attackers to gain escalated privileges and problem virtualbox-bin alsa conflict with other is solved and use this commands:

# emerge --sync
# emerge --ask --oneshot --verbose “>=app-emulation/virtualbox-4.1.8”