[PATCH] auto setup network without netroot

[PATCH] auto setup network without netroot

[Dave Young]

Current dracut network only will be setup when netroot is used. But there are
some cases we need network even without netroot. For example kdump will need
copy vmcore to remote machine via scp or nfs mount. OTOH, if we use dracut as
a recovery system the network is helpful even root is not a network device.

This implementation is based on the manually bring up method. Here add a kernel
cmdline argument rd.neednet. If rd.neednet is set dracut will bring up network
with ifup $INTERFACE -m. If netroot is used we still keep original behavior.

Signed-off-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 dracut.cmdline.7.xml                |    8 ++++++++
 modules.d/40network/net-genrules.sh |   20 ++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

Index: dracut/modules.d/40network/net-genrules.sh
===================================================================
--- dracut.orig/modules.d/40network/net-genrules.sh
+++ dracut/modules.d/40network/net-genrules.sh
@@ -14,7 +14,7 @@ fix_bootif() {
 }
 
 # Don't continue if we don't need network
-[ -z "$netroot" ] && return;
+[ -z "$netroot" ] && ! getargbool 0 rd.neednet && return;
 
 # Write udev rules
 {
@@ -35,17 +35,29 @@ fix_bootif() {
     BOOTIF=$(getarg 'BOOTIF=')
     if [ -n "$BOOTIF" ] ; then
         BOOTIF=$(fix_bootif "$BOOTIF")
-        printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$BOOTIF"
+        if [ -n "$netroot" ]; then
+            printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$BOOTIF"
+        else
+            printf 'ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="%s", RUN+="/sbin/ifup $env{INTERFACE} -m"\n' "$BOOTIF"
+        fi
 
     # If we have to handle multiple interfaces, handle only them.
     elif [ -n "$IFACES" ] ; then
         for iface in $IFACES ; do
-            printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$iface"
+            if [ -n "$netroot" ]; then
+                printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE}"\n' "$iface"
+            else
+                printf 'SUBSYSTEM=="net", ENV{INTERFACE}=="%s", RUN+="/sbin/ifup $env{INTERFACE} -m"\n' "$iface"
+            fi
         done
 
     # Default: We don't know the interface to use, handle all
     else
-        printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE}"\n'
+        if [ -n "$netroot" ]; then
+            printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE}"\n'
+        else
+            printf 'SUBSYSTEM=="net", RUN+="/sbin/ifup $env{INTERFACE} -m"\n'
+        fi
     fi
 
 } > /etc/udev/rules.d/60-net.rules
Index: dracut/dracut.cmdline.7.xml
===================================================================
--- dracut.orig/dracut.cmdline.7.xml
+++ dracut/dracut.cmdline.7.xml
@@ -507,6 +507,14 @@ Required if multiple ip= lines are used.
             <para>turn on/off biosdevname network interface renaming</para>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term>
+            <envar>rd.neednet=</envar><replaceable>&lt;0|1&gt;</replaceable>
+          </term>
+          <listitem>
+            <para>boolean, bring up network even without netroot set</para>
+          </listitem>
+        </varlistentry>
       </variablelist>
     </refsect2>
     <refsect2>

Re: [PATCH] auto setup network without netroot

[Cong Wang]

On Mon, 30 Jan 2012 at 06:43 GMT, Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> Current dracut network only will be setup when netroot is used. But there are
> some cases we need network even without netroot. For example kdump will need
> copy vmcore to remote machine via scp or nfs mount. OTOH, if we use dracut as
> a recovery system the network is helpful even root is not a network device.
>
> This implementation is based on the manually bring up method. Here add a kernel
> cmdline argument rd.neednet. If rd.neednet is set dracut will bring up network
> with ifup $INTERFACE -m. If netroot is used we still keep original behavior.
>

I don't think we really need to introduce a new cmdline, I think we
can re-use ip= cmdline. Currently, if ip= is specified but netroot is
not, ip= will be ignored. We can change this, let dracut bring up
network as long as we have ip=, even we don't have netroot.

Re: [PATCH] auto setup network without netroot

[Dave Young]

On 01/30/2012 04:33 PM, Cong Wang wrote:

> On Mon, 30 Jan 2012 at 06:43 GMT, Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>> Current dracut network only will be setup when netroot is used. But there are
>> some cases we need network even without netroot. For example kdump will need
>> copy vmcore to remote machine via scp or nfs mount. OTOH, if we use dracut as
>> a recovery system the network is helpful even root is not a network device.
>>
>> This implementation is based on the manually bring up method. Here add a kernel
>> cmdline argument rd.neednet. If rd.neednet is set dracut will bring up network
>> with ifup $INTERFACE -m. If netroot is used we still keep original behavior.
>>
> 
> I don't think we really need to introduce a new cmdline, I think we
> can re-use ip= cmdline. Currently, if ip= is specified but netroot is
> not, ip= will be ignored. We can change this, let dracut bring up
> network as long as we have ip=, even we don't have netroot.


For netroot case it is supported as well for no ip= or other network
cmdline, please see the net-genrules.sh code

We will also setup network when rd.neednet=1 in case no special ip=
provided for convenience.

> 
> --
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-- 
Thanks
Dave

Re: [PATCH] auto setup network without netroot

[Cong Wang]

On 01/30/2012 04:51 PM, Dave Young wrote:
> On 01/30/2012 04:33 PM, Cong Wang wrote:
>
>> On Mon, 30 Jan 2012 at 06:43 GMT, Dave Young<dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>  wrote:
>>> Current dracut network only will be setup when netroot is used. But there are
>>> some cases we need network even without netroot. For example kdump will need
>>> copy vmcore to remote machine via scp or nfs mount. OTOH, if we use dracut as
>>> a recovery system the network is helpful even root is not a network device.
>>>
>>> This implementation is based on the manually bring up method. Here add a kernel
>>> cmdline argument rd.neednet. If rd.neednet is set dracut will bring up network
>>> with ifup $INTERFACE -m. If netroot is used we still keep original behavior.
>>>
>>
>> I don't think we really need to introduce a new cmdline, I think we
>> can re-use ip= cmdline. Currently, if ip= is specified but netroot is
>> not, ip= will be ignored. We can change this, let dracut bring up
>> network as long as we have ip=, even we don't have netroot.
>
>
> For netroot case it is supported as well for no ip= or other network
> cmdline, please see the net-genrules.sh code


Irrelevant.

>
> We will also setup network when rd.neednet=1 in case no special ip=
> provided for convenience.
>

With rd.neednet=1 but without ip=, how can you know which nic we need to 
bring up?

Re: [PATCH] auto setup network without netroot

[Dave Young]

On 01/30/2012 04:51 PM, Cong Wang wrote:

> On 01/30/2012 04:51 PM, Dave Young wrote:
>> On 01/30/2012 04:33 PM, Cong Wang wrote:
>>
>>> On Mon, 30 Jan 2012 at 06:43 GMT, Dave Young<dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>  wrote:
>>>> Current dracut network only will be setup when netroot is used. But
>>>> there are
>>>> some cases we need network even without netroot. For example kdump
>>>> will need
>>>> copy vmcore to remote machine via scp or nfs mount. OTOH, if we use
>>>> dracut as
>>>> a recovery system the network is helpful even root is not a network
>>>> device.
>>>>
>>>> This implementation is based on the manually bring up method. Here
>>>> add a kernel
>>>> cmdline argument rd.neednet. If rd.neednet is set dracut will bring
>>>> up network
>>>> with ifup $INTERFACE -m. If netroot is used we still keep original
>>>> behavior.
>>>>
>>>
>>> I don't think we really need to introduce a new cmdline, I think we
>>> can re-use ip= cmdline. Currently, if ip= is specified but netroot is
>>> not, ip= will be ignored. We can change this, let dracut bring up
>>> network as long as we have ip=, even we don't have netroot.
>>
>>
>> For netroot case it is supported as well for no ip= or other network
>> cmdline, please see the net-genrules.sh code
> 
> 
> Irrelevant.
> 
>>
>> We will also setup network when rd.neednet=1 in case no special ip=
>> provided for convenience.
>>
> 
> With rd.neednet=1 but without ip=, how can you know which nic we need to
> bring up?


current behavior of net-genrule.sh is below:

# Default: We don't know the interface to use, handle all

It will be ok and convenient at least when we have only one nic

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-- 
Thanks
Dave

Re: [PATCH] auto setup network without netroot

[Cong Wang]

On 01/30/2012 04:59 PM, Dave Young wrote:
> On 01/30/2012 04:51 PM, Cong Wang wrote:
>
>> On 01/30/2012 04:51 PM, Dave Young wrote:
>>>
>>> We will also setup network when rd.neednet=1 in case no special ip=
>>> provided for convenience.
>>>
>>
>> With rd.neednet=1 but without ip=, how can you know which nic we need to
>> bring up?
>
>
> current behavior of net-genrule.sh is below:
>
> # Default: We don't know the interface to use, handle all
>
> It will be ok and convenient at least when we have only one nic

So, rd.neednet=1 will bring up all when there is no ip=, what kdump 
needs is a cmdline that tells dracut to bring up only the ones we need.

You still don't tell why re-using ip= doesn't work. So far, I think ip= 
can be re-used for kdump case, and is better than your rd.neeednet=1.

Re: [PATCH] auto setup network without netroot

[Dave Young]

On 01/30/2012 05:03 PM, Cong Wang wrote:

> On 01/30/2012 04:59 PM, Dave Young wrote:
>> On 01/30/2012 04:51 PM, Cong Wang wrote:
>>
>>> On 01/30/2012 04:51 PM, Dave Young wrote:
>>>>
>>>> We will also setup network when rd.neednet=1 in case no special ip=
>>>> provided for convenience.
>>>>
>>>
>>> With rd.neednet=1 but without ip=, how can you know which nic we need to
>>> bring up?
>>
>>
>> current behavior of net-genrule.sh is below:
>>
>> # Default: We don't know the interface to use, handle all
>>
>> It will be ok and convenient at least when we have only one nic
> 
> So, rd.neednet=1 will bring up all when there is no ip=, what kdump
> needs is a cmdline that tells dracut to bring up only the ones we need.
> 
> You still don't tell why re-using ip= doesn't work. So far, I think ip=
> can be re-used for kdump case, and is better than your rd.neeednet=1.



How to say...
There's many different configs for network like:
1. ip={dhcp|on|any|dhcp6|auto6|ibft}
2. ip=<interface>:{dhcp|on|any|dhcp6|auto6}
3. ip=<client-IP>:[ <server-id>
]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off}
4. ifname=
5. bootdev=
6. root=nfs:[snip]

They are all possibly be used, IHMO they are not good options for this
patch using. For example there's no NIC specified in 1 and 3, we will
still have to bring up the default

Also this is a general feature, maybe it will be used by users other
than kdump. For kdump I think we can use proper ip= plus rd.neednet=1

-- 
Thanks
Dave

Re: [PATCH] auto setup network without netroot

[Cong Wang]

On 01/30/2012 05:16 PM, Dave Young wrote:
>
> How to say...
> There's many different configs for network like:
> 1. ip={dhcp|on|any|dhcp6|auto6|ibft}
> 2. ip=<interface>:{dhcp|on|any|dhcp6|auto6}
> 3. ip=<client-IP>:[<server-id>
> ]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off}
> 4. ifname=
> 5. bootdev=
> 6. root=nfs:[snip]
>
> They are all possibly be used, IHMO they are not good options for this
> patch using. For example there's no NIC specified in 1 and 3, we will
> still have to bring up the default


Kdump module can make sure that at least one NIC will be specified, if 
there is ip=.

>
> Also this is a general feature, maybe it will be used by users other
> than kdump. For kdump I think we can use proper ip= plus rd.neednet=1
>

Why? If we can re-use ip=, it will imply rd.neednet=1, so again, 
rd.neednet is not needed.

Thanks.

Re: [PATCH] auto setup network without netroot

[Dave Young]

On 01/30/2012 05:31 PM, Cong Wang wrote:

> On 01/30/2012 05:16 PM, Dave Young wrote:
>>
>> How to say...
>> There's many different configs for network like:
>> 1. ip={dhcp|on|any|dhcp6|auto6|ibft}
>> 2. ip=<interface>:{dhcp|on|any|dhcp6|auto6}
>> 3. ip=<client-IP>:[<server-id>
>> ]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off}
>> 4. ifname=
>> 5. bootdev=
>> 6. root=nfs:[snip]
>>
>> They are all possibly be used, IHMO they are not good options for this
>> patch using. For example there's no NIC specified in 1 and 3, we will
>> still have to bring up the default
> 
> 
> Kdump module can make sure that at least one NIC will be specified, if
> there is ip=.
> 
>>
>> Also this is a general feature, maybe it will be used by users other
>> than kdump. For kdump I think we can use proper ip= plus rd.neednet=1
>>
> 
> Why? If we can re-use ip=, it will imply rd.neednet=1, so again,
> rd.neednet is not needed.


why choose ip=? what if user pass ifname= or bootdev= without ip=? I
want to benefit to other user as well, from semantic point of view one
global switch like rd.neednet is more clear then reuse the various other
options.


-- 
Thanks
Dave

Re: [PATCH] auto setup network without netroot

[Cong Wang]

On 01/30/2012 05:49 PM, Dave Young wrote:
> On 01/30/2012 05:31 PM, Cong Wang wrote:
>
>> On 01/30/2012 05:16 PM, Dave Young wrote:
>>>
>>> How to say...
>>> There's many different configs for network like:
>>> 1. ip={dhcp|on|any|dhcp6|auto6|ibft}
>>> 2. ip=<interface>:{dhcp|on|any|dhcp6|auto6}
>>> 3. ip=<client-IP>:[<server-id>
>>> ]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off}
>>> 4. ifname=
>>> 5. bootdev=
>>> 6. root=nfs:[snip]
>>>
>>> They are all possibly be used, IHMO they are not good options for this
>>> patch using. For example there's no NIC specified in 1 and 3, we will
>>> still have to bring up the default
>>
>>
>> Kdump module can make sure that at least one NIC will be specified, if
>> there is ip=.
>>
>>>
>>> Also this is a general feature, maybe it will be used by users other
>>> than kdump. For kdump I think we can use proper ip= plus rd.neednet=1
>>>
>>
>> Why? If we can re-use ip=, it will imply rd.neednet=1, so again,
>> rd.neednet is not needed.
>
>
> why choose ip=? what if user pass ifname= or bootdev= without ip=? I

For kdump, ip= is the one we need, it has the NIC, and dhcp etc, 
everything we need to bring up an NIC.

If ifname= or bootdev= is provided but no ip=, we can just bring the NIC 
up without assigning any IP address.

> want to benefit to other user as well, from semantic point of view one
> global switch like rd.neednet is more clear then reuse the various other
> options.

I can't agree, only specifying ip= also means bringing up network 
apparently.

Re: [PATCH] auto setup network without netroot

[Dave Young]

On 01/30/2012 06:03 PM, Cong Wang wrote:

> On 01/30/2012 05:49 PM, Dave Young wrote:
>> On 01/30/2012 05:31 PM, Cong Wang wrote:
>>
>>> On 01/30/2012 05:16 PM, Dave Young wrote:
>>>>
>>>> How to say...
>>>> There's many different configs for network like:
>>>> 1. ip={dhcp|on|any|dhcp6|auto6|ibft}
>>>> 2. ip=<interface>:{dhcp|on|any|dhcp6|auto6}
>>>> 3. ip=<client-IP>:[<server-id>
>>>> ]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off}
>>>> 4. ifname=
>>>> 5. bootdev=
>>>> 6. root=nfs:[snip]
>>>>
>>>> They are all possibly be used, IHMO they are not good options for this
>>>> patch using. For example there's no NIC specified in 1 and 3, we will
>>>> still have to bring up the default
>>>
>>>
>>> Kdump module can make sure that at least one NIC will be specified, if
>>> there is ip=.
>>>
>>>>
>>>> Also this is a general feature, maybe it will be used by users other
>>>> than kdump. For kdump I think we can use proper ip= plus rd.neednet=1
>>>>
>>>
>>> Why? If we can re-use ip=, it will imply rd.neednet=1, so again,
>>> rd.neednet is not needed.
>>
>>
>> why choose ip=? what if user pass ifname= or bootdev= without ip=? I
> 
> For kdump, ip= is the one we need, it has the NIC, and dhcp etc,
> everything we need to bring up an NIC.
> 
> If ifname= or bootdev= is provided but no ip=, we can just bring the NIC
> up without assigning any IP address.
> 
>> want to benefit to other user as well, from semantic point of view one
>> global switch like rd.neednet is more clear then reuse the various other
>> options.
> 
> I can't agree, only specifying ip= also means bringing up network
> apparently.


Harald, what's your opnion? especially about the previous patch to allow
manually bring up network with like 'ifup eth0 -m'? Can you give comments?

-- 
Thanks
Dave