[LinuxBIOS] how to use ramdisk as rootfs

[zhu shi song]

Dear Lists,
   I can boot my EPIA using Linuxbios.  But I want to
use RAM disk as root file system.  How can I do with
it?
   tks
   zhu

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[Stefan Reinauer]

* zhu shi song  [060707 10:50]:
> Dear Lists,
>    I can boot my EPIA using Linuxbios.  But I want to
> use RAM disk as root file system.  How can I do with
> it?

Use an initial ramdisk (initrd). You can specify it in the bootloader
(ie filo) as initrd=/path/to/initrd in the kernel command line, or
use mkelfImage to produce a single binary from kernel and initrd so it
can be flashed to rom as part of LinuxBIOS.

Stefan

[Russell Whitaker]

On Fri, 7 Jul 2006, Stefan Reinauer wrote:
> zhu shi song  [060707 10:50]:
> > Dear Lists,
> >    I can boot my EPIA using Linuxbios.  But I want to
> > use RAM disk as root file system.  How can I do with
> > it?
>
> Use an initial ramdisk (initrd). You can specify it in the bootloader
> (ie filo) as initrd=/path/to/initrd in the kernel command line, or
> use mkelfImage to produce a single binary from kernel and initrd so it
> can be flashed to rom as part of LinuxBIOS.

Check out www.linux-live.org

It has a series of scripts to run everything from cdrom or usb, and a
script to transfer everything to ram. Both files and dirs are compressed.

There are two distros now using these scripts:
     www.slax.org
     www.zenlive.tuxfamily.org

russ

[zhu shi song]

I must concern two requirements:
(1) I boot my linux from IDE CF card whose capacity is
no more than 128M Bytes.
(2) my ram is large enough(above 1G) for the size of
the whole root file system.
  In the past ,when I use linux-2.4 kernel, I use
initrd-dyn method and can use one tar.gz file just
like initrd transferred to kernel as parameter. The
kernel can uncompress the tar.gz file and mount it on
ramdisk as rootfs.  Unfortunately, initrd-dyn can't
support linux-2.6 kernel.  Can I convert my tar.gz
file to cpio format as initramfs and make kernel
uncompress it and mount it as rootfs on ramdisk
automatically?  I'm not so familiar with either initrd
or initramfs, where can I find more and clear info
about these topics?
  tks
  zhu

--- Russell Whitaker  wrote:
> On Fri, 7 Jul 2006, Stefan Reinauer wrote:
> > zhu shi song  [060707
>
> 10:50]:
> > > Dear Lists,
> > >    I can boot my EPIA using Linuxbios.  But I
>
> want to
> > > use RAM disk as root file system.  How can I do
>
> with
> > > it?
> >
> > Use an initial ramdisk (initrd). You can specify
>
> it in the bootloader
> > (ie filo) as initrd=/path/to/initrd in the kernel
>
> command line, or
> > use mkelfImage to produce a single binary from
>
> kernel and initrd so it
> > can be flashed to rom as part of LinuxBIOS.
>
> Check out www.linux-live.org
>
> It has a series of scripts to run everything from
> cdrom or usb, and a
> script to transfer everything to ram. Both files and
> dirs are compressed.
>
> There are two distros now using these scripts:
>      www.slax.org
>      www.zenlive.tuxfamily.org
>
> russ

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[Ronald G Minnich]

you can build  cpio archive and use it as an initrd.

ron

[Ronald G Minnich]

Ronald G Minnich wrote:
> you can build  cpio archive and use it as an initrd.
>
> ron

here is the script I currently use. Pretend your prototype file system 
is in root_dir

cd root_dir
find . | cpio --create --format=newc > ../initramfs_data.cpio
cd ..
gzip -9 initramfs_data.cpio
#mv  initramfs_data.cpio.gz  /where_kernel_is/linux-2.6.xxx/usr/

[Richard Smith]

> support linux-2.6 kernel.  Can I convert my tar.gz
> file to cpio format as initramfs and make kernel
> uncompress it and mount it as rootfs on ramdisk
> automatically?  I'm not so familiar with either initrd
> or initramfs, where can I find more and clear info
> about these topics?

There is a little bit of info about initramfs in the kernel tree.

/Documentation/filesystems/ramfs-rootfs-initramfs.txt

[Ronald G Minnich]

Richard Smith wrote:
> > support linux-2.6 kernel.  Can I convert my tar.gz
> > file to cpio format as initramfs and make kernel
> > uncompress it and mount it as rootfs on ramdisk
> > automatically?  I'm not so familiar with either initrd
> > or initramfs, where can I find more and clear info
> > about these topics?
>
> There is a little bit of info about initramfs in the kernel tree.
>
> /Documentation/filesystems/ramfs-rootfs-initramfs.txt

I don't recommend initramfs -- just make a cpio initrd. Current 
initramfs support is bug-ridden.

ron

Ronald G Minnich  writes:
> Richard Smith wrote:
> > > support linux-2.6 kernel.  Can I convert my tar.gz
> > > file to cpio format as initramfs and make kernel
> > > uncompress it and mount it as rootfs on ramdisk
> > > automatically?  I'm not so familiar with either initrd
> > > or initramfs, where can I find more and clear info
> > > about these topics?
> >
> > There is a little bit of info about initramfs in the kernel tree.
> >
> > /Documentation/filesystems/ramfs-rootfs-initramfs.txt
>
> I don't recommend initramfs -- just make a cpio initrd. Current 
> initramfs support is bug-ridden.

To be clear a cpio format initrd is referred to as an initramfs.  There
are no real implementation differences between the in kernel and
initrd styles the only question is where does the cpio archive come
from, and how is the cpio archive built.

Since the in kernel cpio archive builder has issues it does make sense
to avoid it.

Eric

[zhu shi song]

In the past I used obsolete libc for kernel2.6. Where
can I get initrd with little footprint suitable for
kernel 2.6 diskless boot?  Now I'm testing  my old
rootfs using initrd as ramdisk rootfs.

tks
    zhu

--- "Eric W. Biederman"  wrote:
> Ronald G Minnich  writes:
> > Richard Smith wrote:
> > > > support linux-2.6 kernel.  Can I convert my
>
> tar.gz
> > > > file to cpio format as initramfs and make kernel
> > > > uncompress it and mount it as rootfs on ramdisk
> > > > automatically?  I'm not so familiar with either
>
> initrd
> > > > or initramfs, where can I find more and clear
>
> info
> > > > about these topics?
> > >
> > > There is a little bit of info about initramfs in
>
> the kernel tree.
> > >

/Documentation/filesystems/ramfs-rootfs-initramfs.txt
> > >
> >
> > I don't recommend initramfs -- just make a cpio
>
> initrd. Current
> > initramfs support is bug-ridden.
>
> To be clear a cpio format initrd is referred to as
> an initramfs.  There
> are no real implementation differences between the
> in kernel and
> initrd styles the only question is where does the
> cpio archive come
> from, and how is the cpio archive built.
>
> Since the in kernel cpio archive builder has issues
> it does make sense
> to avoid it.
>
> Eric

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[zhu shi song]

My existing rootfs is some obsolete for kernel2.6.
Where can I get initrd with little footprint suitable
for kernel 2.6 diskless boot?  Now I'm testing  my old
rootfs using initrd as ramdisk rootfs.

tks
    zhu

--- "Eric W. Biederman"  wrote:
> Ronald G Minnich  writes:
> > Richard Smith wrote:
> > > > support linux-2.6 kernel.  Can I convert my
>
> tar.gz
> > > > file to cpio format as initramfs and make kernel
> > > > uncompress it and mount it as rootfs on ramdisk
> > > > automatically?  I'm not so familiar with either
>
> initrd
> > > > or initramfs, where can I find more and clear
>
> info
> > > > about these topics?
> > >
> > > There is a little bit of info about initramfs in
>
> the kernel tree.
> > >

/Documentation/filesystems/ramfs-rootfs-initramfs.txt
> > >
> >
> > I don't recommend initramfs -- just make a cpio
>
> initrd. Current
> > initramfs support is bug-ridden.
>
> To be clear a cpio format initrd is referred to as
> an initramfs.  There
> are no real implementation differences between the
> in kernel and
> initrd styles the only question is where does the
> cpio archive come
> from, and how is the cpio archive built.
>
> Since the in kernel cpio archive builder has issues
> it does make sense
> to avoid it.
>
> Eric

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[Richard Smith]

On 7/11/06, zhu shi song  wrote:
> My existing rootfs is some obsolete for kernel2.6.
> Where can I get initrd with little footprint suitable
> for kernel 2.6 diskless boot?  Now I'm testing  my old
> rootfs using initrd as ramdisk rootfs.

http://buildroot.uclibc.org/