Re: Building PXE/XIP environment

[Scrap Happy <scrap%GMX.com@localhost>]

Bonjour Jean-Yves,

On 4/21/2011 3:38 AM, Jean-Yves Migeon wrote:
> On 21.04.2011 09:05, Scrap Happy wrote:
> > I need to be able to boot a "standalone" environment
> > for some applications (i.e., one the image is loaded,
> > there are no remaining dependencies on the "server"...
> > no nfs mounts, etc.).
> >
> > Since this is probably an interactive/iterative process
> > (i.e., port some part of the system, determine any
> > dependencies that must be removed, remove them, lather,
> > rinse, repeat), I wonder if there is a straightforward
> > way to create a kernel+filesystem image and then "package"
> > this once it works properly.
> >
> > Any pointers to guides that might facilitate this?
>
> Once you have your system ready to be packaged:
> - use makefs(8) to create the filesystem image:
>      makefs<image file>  <image root directory>

So, if I've built a filesystem "/foo" and verified
everything works as expected after 'chroot /foo',
this (makefs foo.image /foo) will bundle it up for
me?  (presumably, that filesystem should be *quiescent*
when I do this?)

> - note down the resulting file system image file, then compile a kernel
> with:
>
> options MEMORY_DISK_IS_ROOT     # root on memory disk
> options MEMORY_DISK_ROOT_SIZE=40000   # size of fs image in blocks

Is this *literally* the number of blocks in the "foo.image" file?
(i.e., any "overhead" in that file is refected in this count)

I assume you don't want this number too exceed the image's size
as that just wastes memory that could be used for run-time?

OTOH, if the memory disk image will be treated as r/w at run time,
can padding this number give you "extra space" in the resulting file
system?

> - mdsetimage(8) to embed the image in the resulting kernel:
>
>      mdsetimage<kernel>  <image file>
>
> Boot with the resulting<kernel>. If your host system is not NetBSD,
> build these tools via build.sh.

Can I just pass this entire image to the device via PXE?  Or, am
I better off getting the kernel to the device and *then* having
the kernel drag over the image?

Thanks!
--don