ubuntu11.10 system has no sound and Gentoo on the ALSA

Today, Ubuntu 11.10 suddenly lost its voice, the result Sudo/sbin/alsa force-reload to solve the problem, but do not know why.

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What is AlsaALSA is the abbreviation for Advanced Linux Sound architecture, the Advanced Linux Sound architecture, which provides audio and MIDI on Linux operating systems (musical instrument Digital, Music Device Digital Interface) support.　　In the 2.6-series kernel, ALSA has become the default sound subsystem for replacing OSS in the 2.4-series kernel (open Sound system, and opening sound systems). The main features of ALSA include: efficiently supports all types of audio interfaces from consumer entry-level sound cards to professional audio devices, fully modular design, supports symmetric multiple processing (SMP) and thread safety, backward compatibility for OSS, and provides user-space Alsa-lib libraries to simplify application development.the ALSA on the GentooHistorically, Gentoo offers two ways to enable ALSA to run on your system: the kernel's own drive and the external Alsa-driver package. The two scenarios basically accomplish the same task; This makes it extremely difficult and time-consuming to provide support for external packages. Gentoo Maintainers decided not to continue supporting the Alsa-driver package, but rather to focus their resources on the ALSA drive portion of the Linux kernel.　　This guide will focus only on how to configure ALSA with the drive that comes with the kernel itself. Jaroslav Kysela used to be the leader of the project, which began as a driver developed for the 1998 Gravis Ultrasound, which has been developed as a separate package until 2002 when he was introduced into the Linux kernel development version ( 2.5.4-2.5.5) 1.　　Starting with version 2.6, ALSA becomes the default standard audio driver set in the Linux kernel, and OSS is marked as obsolete. ALSA is a fully open source audio driver Assembly, in addition to providing a set of kernel driver modules like OSS, ALSA provides a library of functions specifically for simplifying application authoring, compared to the IOCTL based native programming interfaces provided by OSS, The ALSA function library is more convenient to use. With this function library, developers can easily and quickly develop their own applications, the details are left to the function library internal processing.　　Of course, ALSA also provides a system interface similar to OSS, but ALSA developers recommend that application developers use the Audio function library instead of the driver API. Primary files for Alsa in Linux: include/sound/driver.h sound/core/*.c Note: OSS (Open sound System) is another driver framework for audio in Linux.

Gentoo is a Linux based free operating system that automatically optimizes and customizes almost any application or requirement. The pursuit of extreme configuration, performance, and the top user and developer community, are the hallmarks of the Gentoo experience. The philosophy of Gentoo is freedom and choice. Thanks to a technology called Portage, Gentoo can become an ideal security server, development workstation, professional desktop, gaming system, embedded solution, or something else-what you want it to be. Because of its almost limitless adaptability, Gentoo is called a meta distribution.