FreeBSD source tree https://cgit-dev.freebsd.org/src/atom?h=release%2F9.3.0 2010-11-09T10:59:09Z 2010-11-09T10:59:09Z Rebecca Cran brucec@FreeBSD.org 2010-11-09T10:59:09Z urn:sha1:b1ce21c6efcf01904c5ae425327bfeca3c1b47b5 PR: bin/148894 Submitted by: olgeni 2008-08-20T08:31:58Z Ed Schouten ed@FreeBSD.org 2008-08-20T08:31:58Z urn:sha1:bc093719ca478fe10b938cef32c30b528042cbcd The last half year I've been working on a replacement TTY layer for the FreeBSD kernel. The new TTY layer was designed to improve the following: - Improved driver model: The old TTY layer has a driver model that is not abstract enough to make it friendly to use. A good example is the output path, where the device drivers directly access the output buffers. This means that an in-kernel PPP implementation must always convert network buffers into TTY buffers. If a PPP implementation would be built on top of the new TTY layer (still needs a hooks layer, though), it would allow the PPP implementation to directly hand the data to the TTY driver. - Improved hotplugging: With the old TTY layer, it isn't entirely safe to destroy TTY's from the system. This implementation has a two-step destructing design, where the driver first abandons the TTY. After all threads have left the TTY, the TTY layer calls a routine in the driver, which can be used to free resources (unit numbers, etc). The pts(4) driver also implements this feature, which means posix_openpt() will now return PTY's that are created on the fly. - Improved performance: One of the major improvements is the per-TTY mutex, which is expected to improve scalability when compared to the old Giant locking. Another change is the unbuffered copying to userspace, which is both used on TTY device nodes and PTY masters. Upgrading should be quite straightforward. Unlike previous versions, existing kernel configuration files do not need to be changed, except when they reference device drivers that are listed in UPDATING. Obtained from: //depot/projects/mpsafetty/... Approved by: philip (ex-mentor) Discussed: on the lists, at BSDCan, at the DevSummit Sponsored by: Snow B.V., the Netherlands dcons(4) fixed by: kan 2005-12-04T02:12:43Z Ruslan Ermilov ru@FreeBSD.org 2005-12-04T02:12:43Z urn:sha1:f4e98881073f261956da27827173b990cd9c7bd5 2004-01-21T05:08:51Z Peter Grehan grehan@FreeBSD.org 2004-01-21T05:08:51Z urn:sha1:a2dce78a840a9755cb1d55f2b1b59930c6bd794d Took the opportunity to reduce __i386__ || __ia64__ || __amd64__ || __sparc64__ || __powerpc__ to !__alpha__ reviewed by: gallatin 2003-08-24T18:17:24Z David E. O'Brien obrien@FreeBSD.org 2003-08-24T18:17:24Z urn:sha1:42af95a3c26c2c5f504902cd0d9d0482c29cd033 Also some minor style cleanups. 2003-08-24T00:44:00Z Jake Burkholder jake@FreeBSD.org 2003-08-24T00:44:00Z urn:sha1:8b9698b7112692c553fbe32693793901807211bb 2003-02-19T05:47:46Z Warner Losh imp@FreeBSD.org 2003-02-19T05:47:46Z urn:sha1:a163d034fadcfb4a25ca34a2ba5f491c47b6ff69 Approved by: trb 2003-01-21T08:56:16Z Alfred Perlstein alfred@FreeBSD.org 2003-01-21T08:56:16Z urn:sha1:44956c9863dc03344b03bdf6a83acf4e743f8e50 Merge M_NOWAIT/M_DONTWAIT into a single flag M_NOWAIT. 2002-08-19T23:56:01Z Peter Wemm peter@FreeBSD.org 2002-08-19T23:56:01Z urn:sha1:f457830b8e6b4cda7b505eae88b3af9759adfe72 little more than a place holder, because nothing actually counted the number of 'sc' units to compare it against NSC. A bit more work here is needed so that the scaling of SC_MAX_HISTORY_SIZE and extra_history_size goes up when more sc units are added. But, it does not appear that we can have more than one console yet, so it does not seem particularly urgent. 2001-09-12T08:38:13Z Julian Elischer julian@FreeBSD.org 2001-09-12T08:38:13Z urn:sha1:b40ce4165d5eb3a5de1515245055350ae3dbab8e Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha