recommended method of netbooting kernel/dtb in u-boot?

recommended method of netbooting kernel/dtb in u-boot?

[Chris Friesen]

Hi all,

We've got a powerpc system that uses u-boot.  In our environment on 
bootup u-boot does a DHCP to get networking info, then uses TFTP to get 
the kernel, which then does DHCP again and NFS-mounts the initial root 
filesystem.

What's the standard practice for this sort of thing when using device 
tree blobs?  Do most people use multi-file images or do they TFTP 
scripts to load and execute separate kernel/dtb files?

For multi-part images is there an in-kernel way of generating a file 
containing a kernel and dtb combined?  I saw a patch proposed in 2008 to 
add a uImage.<dt> build target but it was shot down because it used the 
legacy multi-file format.  Is there an equivalent build target that uses 
the FIT format?

Chris

-- 

Chris Friesen
Software Designer

500 Palladium Drive, Suite 2100
Ottawa, Ontario K2N 1C2, Canada
www.genband.com
office:+1.343.883.2717
chris.friesen@genband.com

Re: recommended method of netbooting kernel/dtb in u-boot?

[Kumar Gala]

On Apr 11, 2013, at 10:44 AM, Chris Friesen wrote:

>=20
> Hi all,
>=20
> We've got a powerpc system that uses u-boot.  In our environment on =
bootup u-boot does a DHCP to get networking info, then uses TFTP to get =
the kernel, which then does DHCP again and NFS-mounts the initial root =
filesystem.
>=20
> What's the standard practice for this sort of thing when using device =
tree blobs?  Do most people use multi-file images or do they TFTP =
scripts to load and execute separate kernel/dtb files?
>=20
> For multi-part images is there an in-kernel way of generating a file =
containing a kernel and dtb combined?  I saw a patch proposed in 2008 to =
add a uImage.<dt> build target but it was shot down because it used the =
legacy multi-file format.  Is there an equivalent build target that uses =
the FIT format?


We've normally just done multiple tftp fetches and one grabs dtb and one =
grabs kernel.

- k=

Re: recommended method of netbooting kernel/dtb in u-boot?

[Chris Friesen]

On 04/11/2013 12:12 PM, Kumar Gala wrote:
>
> On Apr 11, 2013, at 10:44 AM, Chris Friesen wrote:
>
>>
>> Hi all,
>>
>> We've got a powerpc system that uses u-boot.  In our environment on
>> bootup u-boot does a DHCP to get networking info, then uses TFTP to
>> get the kernel, which then does DHCP again and NFS-mounts the
>> initial root filesystem.
>>
>> What's the standard practice for this sort of thing when using
>> device tree blobs?  Do most people use multi-file images or do they
>> TFTP scripts to load and execute separate kernel/dtb files?
>
> We've normally just done multiple tftp fetches and one grabs dtb and
> one grabs kernel.

Do you hardcode the path to the file in the firmware?  Or do you upload 
a script that knows the path to the file?

In our case the path to the boot file(s) depends on which slot the card 
being booted has been inserted in.  The DHCP server knows what the path 
is, so it can set dhcpd.conf appropriately, but we need to get that 
information to the firmware on the card being booted.

Chris

Re: recommended method of netbooting kernel/dtb in u-boot?

[Ira W. Snyder]

On Thu, Apr 11, 2013 at 12:39:00PM -0600, Chris Friesen wrote:
> On 04/11/2013 12:12 PM, Kumar Gala wrote:
> >
> > On Apr 11, 2013, at 10:44 AM, Chris Friesen wrote:
> >
> >>
> >> Hi all,
> >>
> >> We've got a powerpc system that uses u-boot.  In our environment on
> >> bootup u-boot does a DHCP to get networking info, then uses TFTP to
> >> get the kernel, which then does DHCP again and NFS-mounts the
> >> initial root filesystem.
> >>
> >> What's the standard practice for this sort of thing when using
> >> device tree blobs?  Do most people use multi-file images or do they
> >> TFTP scripts to load and execute separate kernel/dtb files?
> >
> > We've normally just done multiple tftp fetches and one grabs dtb and
> > one grabs kernel.
> 
> Do you hardcode the path to the file in the firmware?  Or do you upload 
> a script that knows the path to the file?
> 
> In our case the path to the boot file(s) depends on which slot the card 
> being booted has been inserted in.  The DHCP server knows what the path 
> is, so it can set dhcpd.conf appropriately, but we need to get that 
> information to the firmware on the card being booted.
> 

Hello Chris,

I use a hardware setup which sounds similar to yours. The DHCP server
controls which file is sent to each card.

I use the FIT image format to combine a kernel, dtb, and initrd in one
package. Then the U-Boot command "dhcp $address" sets up the network and
tftp's the filename sent by the DHCP server. You don't need to invoke
the U-Boot command "tftp" if you only have one image. "dhcp" is enough.

I used the U-Boot doc/uImage.FIT/*.its examples to get started, and
wrote my own custom .its file for my board. I don't use anything other
than the vmlinux.bin.gz provided by the kernel build.

Hope it helps,
Ira

Re: recommended method of netbooting kernel/dtb in u-boot?

[Chris Friesen]

On 04/11/2013 01:50 PM, Ira W. Snyder wrote:

> I use a hardware setup which sounds similar to yours. The DHCP server
> controls which file is sent to each card.
>
> I use the FIT image format to combine a kernel, dtb, and initrd in one
> package.
>
> <snip>
>
> I used the U-Boot doc/uImage.FIT/*.its examples to get started, and
> wrote my own custom .its file for my board. I don't use anything other
> than the vmlinux.bin.gz provided by the kernel build.

Okay, that's a good data point, thanks.

Chris