[ptxdist] Creating links in the root filesystem

[ptxdist] Creating links in the root filesystem

[Matthias Klein]

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Hello,

I try to put links into the read-only rootfs which should point into a 
RAM filesystem.
For example I want to put the resolv.conf file into the tmpfs which is 
mounted at /tmp that the DHCP client can modify that file at runtime.

I tried to create a link in the projectroot:

cd projectroot/etc
ln -s ../tmp/resolv.conf resolv.conf


But then I get the following error with a "ptx go":

-------------------------------------
target: os-release.targetinstall.post
-------------------------------------

finished target os-release.targetinstall.post
make: *** No rule to make target 
`/home/user/development/bsp/branch2_tx53/projectroot/etc/resolv.conf', 
needed by 
`/home/user/development/bsp/branch2_tx53/platform-optimeas-tx53/state/rootfs.targetinstall'. 
  Stop.

If I create an empty file at projectroot/tmp/resolv.conf the file will 
be copied in the rootfs instead if the link...


What is the right way to create such links?
If I create an own package (in + rule) which creates these links, how 
can I ensure that my package is called as the last package to overwrite 
files from other packages ?


Best regards,

Matthias

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Re: [ptxdist] Creating links in the root filesystem

[Michael Olbrich]

Hi,

On Mon, Jan 21, 2013 at 10:07:09AM +0000, Matthias Klein wrote:
> I try to put links into the read-only rootfs which should point into
> a RAM filesystem.
> For example I want to put the resolv.conf file into the tmpfs which
> is mounted at /tmp that the DHCP client can modify that file at
> runtime.
> 
> I tried to create a link in the projectroot:
> 
> cd projectroot/etc
> ln -s ../tmp/resolv.conf resolv.conf
> 
> 
> But then I get the following error with a "ptx go":
> 
> -------------------------------------
> target: os-release.targetinstall.post
> -------------------------------------
> 
> finished target os-release.targetinstall.post
> make: *** No rule to make target `/home/user/development/bsp/branch2_tx53/projectroot/etc/resolv.conf',
> needed by `/home/user/development/bsp/branch2_tx53/platform-optimeas-tx53/state/rootfs.targetinstall'.
> Stop.

With 'install_alternative' ptxdist follows links and tries to install the
contents, so this cannot work.

> If I create an empty file at projectroot/tmp/resolv.conf the file
> will be copied in the rootfs instead if the link...

For /etc/resolv.conf newer versions of ptxdist have an option to make it a
link to /run/resolv.conf, which is a better location as /tmp/.

> What is the right way to create such links?

	@$(call install_link, rootfs, /run/resolv.conf, /etc/resolv.conf)

> If I create an own package (in + rule) which creates these links,
> how can I ensure that my package is called as the last package to
> overwrite files from other packages ?

That's not possible. But you can disable all files in rootfs and install
you're one versions with install_link. For everything else you need to
copy the rules into your BSP and modify them.

Michael

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