diff options
| author | jbranso@dismail.de <jbranso@dismail.de> | 2024-10-12 10:36:49 -0400 |
|---|---|---|
| committer | Samuel Thibault <samuel.thibault@ens-lyon.org> | 2024-10-13 23:38:08 +0200 |
| commit | 168d8955145bb010c1b162c1e23af8a1e9f4fb2d (patch) | |
| tree | 61c3ce96aee26fbc091883f2207289c89bedb538 /hurd/libmachdev.mdwn | |
| parent | 16b9a3b8bd8f2c1e4312133dbce05d0a96fa5b73 (diff) | |
document libmachdev
* hurd/libmachdev.mdwn: new file.
* hurd/documentation.mdwn: link to libmachdev
Message-ID: <20241012143852.2101-2-jbranso@dismail.de>
Diffstat (limited to 'hurd/libmachdev.mdwn')
| -rw-r--r-- | hurd/libmachdev.mdwn | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/hurd/libmachdev.mdwn b/hurd/libmachdev.mdwn new file mode 100644 index 00000000..3f8634e4 --- /dev/null +++ b/hurd/libmachdev.mdwn @@ -0,0 +1,28 @@ +[[!meta copyright="Copyright © 2024 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +GNU/Linux is a monolithic kernel, meaning that a lot of functionality +is baked into the kernel, including filesystems like `ext4` or `xfs`. +Alternatively, the Hurd's filesystems are in userspace, but our disk +device drivers are baked into the GNU Mach kernel image (via +[[DDE|hurd/dde]]). With [[rumpdisk|hurd/rump/rumpdisk]], the Hurd can +use SSDs with userspace device drivers! RumpDisk uses `libmachdev` as +a helper library. + +`libmachdev` exposes devices to userspace via some Mach `device-*` RPC +calls. `libmachdev` provides a trivfs that intercepts the +`device_open` RPC, which the `/dev` node uses. It also fakes a +filesystem node, so you can mount a `netfs` onto it. You still have +to implement `device_read` and `device_write` yourself, but that code +runs in userspace. An example of this can be found in +`rumpdisk/block-rump.c`. + +If [[serverboot V2|open_issues/serverbootv2]] is written, then +`libmachdev` could be simplified or maybe removed. |