document kernel command-line parameters

docs/tinyramfs.cmdline.7

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+.\" Generated by scdoc 1.11.0
+.\" Complete documentation for this program is not available as a GNU info page
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.nh
+.ad l
+.\" Begin generated content:
+.TH "tinyramfs.cmdline" "7" "2020-09-07"
+.P
+.SH NAME
+.P
+Tinyramfs - kernel command-line parameters
+.P
+.SH DESCRIPTION
+.P
+Tinyramfs provides a way to control configuration dynamically via
+kernel parameters without needing to regenerate initramfs image.\& 
+.P
+.SS MAN PAGE SYNTAX
+.P
+.nf
+.RS 4
+|   - OR
+\&.\&.\&. - can be repeated
+.fi
+.RE
+.P
+.SH GENERAL PARAMETERS
+.P
+\fBdebug\fR=1
+.P
+.RS 4
+Enable debug mode.\&
+.P
+.RE
+\fBbreak\fR=breakpoint
+.P
+.RS 4
+Specify breakpoint where shell should be invoked.\& Useful for
+debugging.\& List of supported breakpoints:
+.P
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+keymap
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+devmgr
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+root
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+boot
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+luks
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+lvm
+
+.RE
+.P
+.RE
+\fBroot\fR=UUID|LABEL|/dev/*|PARTUUID
+.P
+.RS 4
+Specify which way tinyramfs will use to look up root filesystem.\&
+.P
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+UUID     - lookup device by uuid
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+LABEL    - lookup device by label
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+/dev/*   - lookup device by full path
+.RE
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.IP \(bu 4
+.\}
+PARTUUID - lookup device by partition uuid
+
+.RE
+.P
+Initramfs must contain \fBblkid\fR(8) for ability to use UUID, LABEL,
+PARTUUID.\& Note that PARTUUID only supported in util-linux \fBblkid\fR(8).\&
+.P
+.RE
+\fBroot_type\fR|\fBrootfstype\fR=type
+.P
+.RS 4
+Explicitly set root filesystem type.\& Kernel must support specified type.\&
+.P
+.RE
+\fBrootdelay\fR=delay
+.P
+.RS 4
+Specify maximum number of seconds to wait for root device.\& Default is 30.\&
+.P
+.RE
+\fBroot_opts\fR|\fBrootflags\fR=opts
+.RS 4
+.P
+See \fBfstab\fR(5) fourth field.\&
+.P
+.RE
+.SH HOOKS PARAMETERS
+.P
+Initramfs must contain appropriate hooks for ability to use below parameters.\&
+.P
+.SS LVM
+.P
+\fBlvm_tag\fR=tag
+.P
+.RS 4
+Specify LVM tag which will be used to trigger LVM.\& This option will be
+ignored if \fBlvm_name\fR/\fBlvm_group\fR was specified.\&
+.P
+.RE
+\fBlvm_name\fR=name
+.P
+.RS 4
+Specify LVM name which will be used to trigger LVM.\& \fBlvm_group\fR must be
+specified.\&
+.P
+.RE
+\fBlvm_group\fR=group
+.P
+.RS 4
+Specify LVM group which will be used to trigger LVM.\&
+.P
+.RE
+\fBlvm_discard\fR=1
+.P
+.RS 4
+Pass issue_discards to lvm.\& Leave empty to disable.\& Useful for SSD's.\&
+.P
+.RE
+.SS LUKS
+.P
+\fBluks_name\fR=name
+.P
+.RS 4
+Specify which name will be registered to mapping table after cryptsetup
+unlocks LUKS root.\&
+.P
+.RE
+\fBluks_root\fR=UUID|LABEL|/dev/*|PARTUUID
+.P
+.RS 4
+See \fBroot\fR for details.\&
+.P
+.RE
+\fBluks_discard\fR=1
+.P
+.RS 4
+Pass --allow-discards to \fBcryptsetup\fR.\& Leave empty to disable.\& Useful for
+SSD's, but you must know that security will be decreased.\&
+.P
+.RE
+.SH EXAMPLES
+.P
+.SS ROOT
+.P
+.nf
+.RS 4
+vmlinuz initrd=initramfs root=/dev/sda1 \&.\&.\&.
+.fi
+.RE
+.P
+.SS DISABLE DISCARD
+.P
+.nf
+.RS 4
+vmlinuz initrd=\\initramfs luks_discard= lvm_discard= \&.\&.\&.
+.fi
+.RE
+.P
+.SS PASS ARGUMENTS TO REAL INIT
+.P
+.nf
+.RS 4
+vmlinuz initrd=\\initramfs \&.\&.\&. -- args
+.fi
+.RE
+.P
+.SH SEE ALSO
+.P
+\fBtinyramfs\fR(8) \fBtinyramfs.\&config\fR(5) \fBtinyramfs.\&hooks\fR(7)