src/sys/dev/nmdm, branch releng/12.0

sys/dev: further adoption of SPDX licensing ID tags.

2017-11-20T19:36:21Z

Mainly focus on files that use BSD 3-Clause license. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. Special thanks to Wind River for providing access to "The Duke of Highlander" tool: an older (2014) run over FreeBSD tree was useful as a starting point.

Renumber copyright clause 4

2017-02-28T23:42:47Z

Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann Pull Request: https://github.com/freebsd/freebsd/pull/96

Fix issue with nmdm and leading zeros in device name.

2014-09-10T05:44:15Z

The nmdm code enforces a number between the 'nmdm' and 'A|B' portions of the device name. This is then used as a unit number, and sprintf'd back into the tty name. If leading zeros were used in the name, the created device name is different than the string used for the clone-open (e.g. /dev/nmdm0001A will result in /dev/nmdm1A). Since unit numbers are no longer required with the updated tty code, there seems to be no reason to force the string to be a number. The fix is to allow an arbitrary string between 'nmdm' and 'A|B', within the constraints of devfs names. This allows all existing user of numeric strings to continue to work, and also allows more meaningful names to be used, such as bhyve VM names. Tested on amd64, i386 and ppc64. Reported by: Dave Smith PR: 192281 Reviewed by: neel, glebius Phabric: D729 MFC after: 3 days

Make nmdm(4) destroy devices when both sides of a pair are disconnected.

2013-12-18T12:53:48Z

This makes it possible to kldunload nmdm.ko when there are no users of it. Reviewed by: kib Sponsored by: Nginx, Inc.

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

2011-11-07T06:44:47Z

This means that their use is restricted to a single C file.

- Remove an unnecessary memory barrier from an atomic op.

2009-06-09T13:33:03Z

- Use the per-softc mutex to protect the softc data in the callout routine rather than letting it run without any locks whatsoever.

Last minute TTY API change: remove mutex argument from tty_alloc().

2009-05-29T06:41:23Z

I don't want people to override the mutex when allocating a TTY. It has to be there, to keep drivers like syscons happy. So I'm creating a tty_alloc_mutex() which can be used in those cases. tty_alloc_mutex() should eventually be removed. The advantage of this approach, is that we can just remove a function, without breaking the regular API in the future.

Make nmdm(4) use MPSAFE callouts.

2008-11-19T21:07:33Z

For some reason the nmdm(4) driver doesn't use CALLOUT_MPSAFE, even though we live in the MPSAFE TTY era. Add the CALLOUT_MPSAFE flags. System survives.

Integrate the new MPSAFE TTY layer to the FreeBSD operating system.

2008-08-20T08:31:58Z

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

Don't enforce unique device minor number policy anymore.

2008-06-11T18:55:19Z

Except for the case where we use the cloner library (clone_create() and friends), there is no reason to enforce a unique device minor number policy. There are various drivers in the source tree that allocate unr pools and such to provide minor numbers, without using them themselves. Because we still need to support unique device minor numbers for the cloner library, introduce a new flag called D_NEEDMINOR. All cdevsw's that are used in combination with the cloner library should be marked with this flag to make the cloning work. This means drivers can now freely use si_drv0 to store their own flags and state, making it effectively the same as si_drv1 and si_drv2. We still keep the minor() and dev2unit() routines around to make drivers happy. The NTFS code also used the minor number in its hash table. We should not do this anymore. If the si_drv0 field would be changed, it would no longer end up in the same list. Approved by: philip (mentor)