For kdump we need scp vmcore to remote machine, the nic to be used is
not limited to netroot one. we need a feature for manually bringing up
network interface. Also it is useful for emergency shell with
ssh-client for recovery or test purpose
I implement this by adding one argument to ifup script, user can use
`/sbin/ifup eth0 -m` to bring up eth0, note ifup will regard it a
manual operation for the nic specified in 1st argument if there's
the 2nd argument.
If same nic is used for netroot the 2nd argument will be ignored,
in this case we will leave netroot bring up it automatically to
avoid side effect. And in this case hooks such as kdump will need to
execute after netroot mounted.
`ifup eth0 -m` will create /tmp/net.eth0.manualup stamp file,
later dhclient-script can check this and pass $2 to netroot,
then netroot script will bring eth0 up
Thanks for comments and suggestions from David Dillow.
Signed-off-by: Dave Young <dyoung@redhat.com>
When booting with nfsroot, dracut doesn't necessarily set the initial
hostname correctly.
According to dhcp-options(5), the name may or may not be qualified with
the local domain. It goes on to say "it is preferable to use the
domain-name option to specify the domain name".
So dhclient-script needs to be able to handle the cases: a) where
host-name is fully qualified and domain name is also specified; b)
where hostname is fully qualified and the domain is not separately
specified; c) where host-name is "short" and domain-name is also
specified; and d) do its best where host-name is short but domain-name
is not specified.
The dhclient-script in initramfs does not handle case "c", apparently
the preferred situation properly, setting hostname to "short".
https://bugzilla.redhat.com/show_bug.cgi?id=756347
We want all "/var/run" information to live in /dev/.run, until the real
root is mounted.
Therefore we mount a tmpfs on /dev/.run, which can/will be bind/move mounted
on /var/run later on.
The manpage for dhclient-script says:
Before actually configuring the address, dhclient-script should
somehow ARP for it and exit with a nonzero status if it receives a
reply.
By using arping in dracut this is very easy, since arping has a
specific option to do just that.
The usual approach to setting mtus is to set the interface down,
set the mtu then set the interface back up again. Modern hardware
and/or drivers may support setting this on the fly, so we try
this and fall back to the old behaviour it it doesn't work.
In addition this patch only allows mtus greater than 576, this is
taken from debian/ubuntu dhclient-script.
The Bug causing dhclient to recall BIND has been identified:
dhclient-script runs with #!/bin/sh -e, causing setup_interface
to fail if no hostname is provided by dhcp as it is the last statement
in that function.
Instead of configuring devices when they are ready, ifup and
dhclient-script write script files which are then sourced by
netroot.
This solves the problem of having multiple interfaces and not knowing
which one to use for dhcp or default route. This way, netroot (which
is serialized anyway) configures the interface before calling the root
handler and deconfigures it if the handler failed.
Example: root=nfs:server:path and ip=dhcp with eth0 and eth1 receiving
a dhcp reply, but eth0 is the correct one to use.
Assuming eth1 is the first to receive the dhcp-reply, netroot starts
and configures eth1. nfsroot is run but fails, so eth1 is deconfigured. If
eth0 has received a dhcp-reply (or not, then we wait) the other locked
netroot process starts and tries with eth0 and succeeds.
Multiline conditionals ( && { ... } ) should use if, function
declarations go to the top of the file, add/update comments and remove
some unnecessary clutter.
This changes the network config to run dhclient from within udev, and
allows multiple dhclients to run at once. It also sets the hostname and
adds a kernel command line option 'netdebug' to help debug network issues.
All modules now live in a subdirectory /modules.d. Each module is
self-contained -- it should contain everything that it will install
on the initrd. All modules must include a script named install, which
will be sourced by dracut. This script should do the actual file installation
using inst methods. The moddir variable will point to the full path to the
module dracut is currently working on.
As usual, this patch series applies on top of my previous patch series,
and is available as normalize-modules from http://git.fnordovax.org/dracut.
Static interfaces are still configured on the fly as we add them, but
discussions on the mailing list have suggested that we need to have finer
control over bringing up dhcp interfaces.
The default hook just runs all the requested dhclients in parallel and waits
for them to all return. If you need something more complicated than this, or
need to have more control over bringing interfaces up, you will probably need
to override some stuff in the 40network hook.
Provided that you are configuring them via DHCP. RARP, BOOTP, and static
configuration are not written yet.
Also, adding nic drivers really bloats the initrd.
I am looking for feedback on these patches from people who actually implement
booting over the network. This patch series does not include support for that
yet -- you will not find nfsroot= handling, or booting to a fs supplied by
dhcp yet. I do want to make it as easy as possible to add support for booting
over the network, as well as making it easy for people to customize things to
meet their site requirements.
This patch series is also available as the network-configurability branch at
http://git.fnordovax.org/dracut. It may be rebased without warning to keep
it in sync with the rest of dracut.
Harald Hoyer