Re: Question on adding a firmware ihex file in the kernel source

[Murali Karicheri]

On 08/20/2015 07:15 PM, David Woodhouse wrote:
> On Thu, 2015-08-20 at 17:46 -0400, Murali Karicheri wrote:
> > All,
> >
> > Please help me understand the procedure to add a firmware ihex file to
> > kernel source tree under firmware/ folder. The README.AddingFirmware
> > file explains that file should be added to
> > git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git and
> > the patch for the same to be send to linux-firmware@xxxxxxxxxxx And this
> > requires it to be in binary form. How does then that end up in the
> > firmware/ folder of the Linux source tree as an ihex file?
>
> You cannot do that. The old firmware/ directory in the source tree is
> incomplete, out of date and scheduled for deletion.
>
> Firmware should *only* go into the separate linux-firmware.git
> repository.
>
> > I would like to have one of the  firmware statically built into the
> > kernel as it is needed to be loaded even before file system is
> > initialized in kernel (network driver firmware).
>
> Do not do that. It is believed by many to be a violation of the GPL.
>
> If the firmware is needed to mount the root file system, then you can
> put it into an initramfs and load it that way, rather than building it
> into the GPL'd kernel image.
Can you point me to a script in initramfs that I can use to switch 
rootfs using switch_root during kernel boot up?

For example, in my case, the PCIe serdes firmware is required to 
initialize PCIe to use SATA harddisk. So I plan to put the firmware in 
initramfs to request_firmware() and initialize the serdes so that PCIe 
become functional so that at a later point in bootup, I can switch my 
rootfs to the rootfs on harddisk using switch_root

Murali

>


--
Murali Karicheri
Linux Kernel, Keystone
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