From 96b0434c25be8c73822a679be35b29ca5263baea Mon Sep 17 00:00:00 2001 From: Will Drewry Date: Wed, 9 Jun 2010 17:47:38 -0500 Subject: CHROMIUM: dm: boot time specification of dm= This is a wrap-up of three patches pending upstream approval. I'm bundling them because they are interdependent, and it'll be easier to drop it on rebase later. 1. dm: allow a dm-fs-style device to be shared via dm-ioctl Integrates feedback from Alisdair, Mike, and Kiyoshi. Two main changes occur here: - One function is added which allows for a programmatically created mapped device to be inserted into the dm-ioctl hash table. This binds the device to a name and, optional, uuid which is needed by udev and allows for userspace management of the mapped device. - dm_table_complete() was extended to handle all of the final functional changes required for the table to be operational once called. 2. init: boot to device-mapper targets without an initr* Add a dm= kernel parameter modeled after the md= parameter from do_mounts_md. It allows for device-mapper targets to be configured at boot time for use early in the boot process (as the root device or otherwise). It also replaces /dev/XXX calls with major:minor opportunistically. The format is dm="name uuid ro,table line 1,table line 2,...". The parser expects the comma to be safe to use as a newline substitute but, otherwise, uses the normal separator of space. Some attempt has been made to make it forgiving of additional spaces (using skip_spaces()). A mapped device created during boot will be assigned a minor of 0 and may be access via /dev/dm-0. An example dm-linear root with no uuid may look like: root=/dev/dm-0 dm="lroot none ro, 0 4096 linear /dev/ubdb 0, 4096 4096 linear /dv/ubdc 0" Once udev is started, /dev/dm-0 will become /dev/mapper/lroot. Older upstream threads: http://marc.info/?l=dm-devel&m=127429492521964&w=2 http://marc.info/?l=dm-devel&m=127429499422096&w=2 http://marc.info/?l=dm-devel&m=127429493922000&w=2 Latest upstream threads: https://patchwork.kernel.org/patch/104859/ https://patchwork.kernel.org/patch/104860/ https://patchwork.kernel.org/patch/104861/ Bug: 27175947 Signed-off-by: Will Drewry Review URL: http://codereview.chromium.org/2020011 Change-Id: I92bd53432a11241228d2e5ac89a3b20d19b05a31 --- Documentation/kernel-parameters.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/kernel-parameters.txt') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 742f69d18fc8..b02f027cba72 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -56,6 +56,7 @@ parameter is applicable: BLACKFIN Blackfin architecture is enabled. CLK Common clock infrastructure is enabled. CMA Contiguous Memory Area support is enabled. + DM Device mapper support is enabled. DRM Direct Rendering Management support is enabled. DYNAMIC_DEBUG Build in debug messages and enable them at runtime EDD BIOS Enhanced Disk Drive Services (EDD) is enabled @@ -915,6 +916,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. dis_ucode_ldr [X86] Disable the microcode loader. + dm= [DM] Allows early creation of a device-mapper device. + See Documentation/device-mapper/boot.txt. + + dmasound= [HW,OSS] Sound subsystem buff + dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, this option disables the debugging code at boot. -- cgit v1.2.3