[yocto] Core-image-minimal-initramfs (Second ping)

[Chris Tapp]

Hi Bill,

On 8 Nov 2013, at 23:13, Bill Martin wrote:

> Please refer to my question in Volume 8 issue 35. I am very desperate in wanting to use the initramfs in m yoctobuild for an embedded x86 target architecture. I am using Yocto Dylan 9.0.2 for crown bay.
> 
> The root directory for my boot is in /dev/sda1
> 
> After normal boot, the root directory is presumably at /dev/sda. Hence my grub has "root (hd0,0)"
> 
> My grub 0.97 initrd command looks good
> 
> My dmesg spits out information and stops at the line
> 
> XT3-fs: mounted filesystem with ordered data
> 
> 
> And that's where it ends up. No panic. 
> 
> I noticed in meta/recipes-core/images the core-image-minimal-initramfs.bb has its IMAGE_ROOT size set to 8192. Is that too small?
> 
> I found absolutely no help in the Yocto documentation on this initramfs stuff. 

There's plenty of information else where on this as it's one of the 'standard' ways of booting. The Yocto documentation focuses more on the Yocto-specific issues, though there are also some really good 'getting started' guides which go into much more detail.

http://en.wikipedia.org/wiki/Initramfs may be a good starting point.

> I found a CONFIG_INITRAMFS_SOURCE and read that this tells the kernel where the initramfs is. I am not sure if I need to set it. Again, no Yocto documentation on how to use one of its builds!!!!!

No, there should be no need for you to set this.

> I presume my grub stage 1 and stage 2 completed and by the time my dmesg command dumps out messages, init is running. In fact I did see a familiar message that is in the init file.

Do you mean you invoked the dmesg command or were you seeing kernel boot messages? These will be shown before init runs.

> I googled all day on what this problem could be. Unfortunately a variety of different causes. I don't know where to begin.
> 
> I did see a question in May 2012 from a guy wanting to see if Yocto supports INITRAMFS. The responder was referring to Grub 2.0 and said in the kernel command initrd=config-image-minimal<target>.cpio.gz /dev/ram0

I think that should be root=/dev/ram0 at the end.

> Is there someone out there, especially from Yocto, who at least tested the capability of Core-image-minimal-initramfs? And not on the simulator but in a real boot?

From my experience, these things are all very well tested, especially at release time.

How did you install the image onto your target? Did you use the .hddimg file or something else?

Can you connect to the console on the system (e.g. serial)? You may need to enable it on the kernel command line with something like console=tty0 console=ttyS0,115200n8

Chris Tapp

opensource at keylevel.com
www.keylevel.com



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