[Buildroot] Starting from scratch fails - how do I get to a basic PXE boot?

[Buildroot] Starting from scratch fails - how do I get to a basic PXE boot?

[Bart J. Smit]

After a string of issues with custom kernels, I thought I'd try with a defconfig from scratch. I deleted the buildroot tree and unpacked the buildroot tarball again. I ran:

$ make menuconfig

kernel changes for VM:
	BR2_LINUX_KERNEL=y
	BR2_LINUX_KERNEL_DEFCONFIG=qemu_x86

changes for PXE boot:
	BR2_TARGET_ROOTFS_TAR=n
	BR2_TARGET_ROOTFS_INITRAMFS=y
	BR2_TARGET_ROOTFS_CPIO=y
	BR2_TARGET_ROOTFS_CPIO_GZIP=y

$ make

This went along quite happy for a while and then halted on:

>>> linux 3.3.7 Configuring
cp /home/buildroot/buildroot/output/build/linux-3.3.7/arch/x86/configs/qemu_x86_defconfig /home/buildroot/buildroot/output/build/linux-3.3.7/arch/x86/configs/buildroot_defconfig
cp: cannot stat `/home/buildroot/buildroot/output/build/linux-3.3.7/arch/x86/configs/qemu_x86_defconfig': No such file or directory
make: *** [/home/buildroot/buildroot/output/build/linux-3.3.7/.stamp_configured] Error 1

So I ran:

$ cp output/build/linux-3.3.7/arch/x86/configs/i386_defconfig output/build/linux-3.3.7/arch/x86/configs/qemu_x86_defconfig
$ make

And this built successfully. I?m testing on a ESXi 4 guest (VM hardware level 7, LSI Logic Parallel SCSI disk, Intel E1000 NIC).
However, when I PXE boot from this, the VM stalls with these last lines:

[ 	2.208499] nf _conntrack version 0.5.0 (16068 buckets, 64272 Max) 
[ 	2.208876] ctnetlink v0.93: registering with nfnetlink. 
[ 	2.209472] ip_tables: (C) 2000-2006 Netfilter Core TeaM 
[ 	2.209692] TCP cubic registered 
[ 	2.209999] input: IMPS/2 Generic Wheel House as /devices/platforM/i8842/serio1/input/input2 
[ 	2.210496] Initializing XFRH netlink socket 
[ 	2.210912] NET: Registered protocol faMily 10 
[ 	2.211103] ip6_tables: (C) 2000-2006 Netfilter Core Team
[ 	2.211141] IPv6 over IPv4 tunneling driver 
[ 	2.212437] NET: Registered protocol faMily 17 
[ 	2.212476] Registering the dns_resolver key type 
[ 	2.212513] Using IPI No-Shortcut Mode 
[ 	2.212791] registered taskstats version 1 
[ 	2.216653] Magic number: 4:891:476 
[ 	2.216690] console [netcon0] enabled 
[ 	2.216728] netconsole: network logging started 
[ 	2.216875] Freeing unused kernel MeMory: 1000k freed 
[ 	2.217135] Write protecting the kernel text: 6392k 
[ 	2.217190] Write protecting the kernel read-only data: 2888k 
Starting logging: ON 
Initializing random number generator ... done.
Starting network ... 
[ 	2.227418] ip used greatest stack depth: 6392 bytes left

What steps did I miss? Is there a better/easier way to get from a clean buildroot to a working PXE setup?

Also, how do I start from scratch more quickly? Is it enough to delete .config to clear all my changes?

Thanks,

Bart...

[Buildroot] Starting from scratch fails - how do I get to a basic PXE boot?

[Thomas Petazzoni]

Le Thu, 12 Jul 2012 10:54:27 +0000,
"Bart J. Smit" <bart@smits.co.uk> a ?crit :

> kernel changes for VM:
> 	BR2_LINUX_KERNEL=y
> 	BR2_LINUX_KERNEL_DEFCONFIG=qemu_x86

This line doesn't make sense, since the kernel does not have a
arch/x86/configs/qemu_x86_defconfig file. For x86, only two defconfigs
are available: i386 and x86_64.

> What steps did I miss? Is there a better/easier way to get from a clean buildroot to a working PXE setup?

Does PXE has anything to do with this? I think PXE just boots a kernel
+ optionally an initrd/initramfs, no?

Regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] Starting from scratch fails - how do I get to a basic PXE boot?

[Bart J. Smit]

Hi Thomas,

I was under the impression from the on-line help that the BR2_LINUX_KERNEL_DEFCONFIG option had to specify one of the defconfig files from the configs directory. 

I've changed the defconfig option to
	BR2_LINUX_KERNEL_DEFCONFIG=i386

It now builds without error, but booting the VM from the resulting bzImage and rootfs.cpio.gz causes it to stall at the same point as before. Could this be because I haven't cleaned the config? Any thoughts on how to wipe the slate clean? Will make clean do the trick?

I don't think PXE has any influence on the problem - it's just the method I'm using to boot. There's obviously no block device other than the initial ramdisk.

I just want to get to a simple booting system and add in complexity from there. It seems I'm still missing a vital component. There must be others on the list who are booting a i386 embedded system.

Bart...

-----Original Message-----
Date: Fri, 13 Jul 2012 00:13:41 +0200
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: buildroot at busybox.net
Subject: Re: [Buildroot] Starting from scratch fails - how do I get to
	a basic PXE boot?
Message-ID: <20120713001341.046da315@skate>
Content-Type: text/plain; charset=UTF-8

Le Thu, 12 Jul 2012 10:54:27 +0000,
"Bart J. Smit" <bart@smits.co.uk> a ?crit :

> kernel changes for VM:
> 	BR2_LINUX_KERNEL=y
> 	BR2_LINUX_KERNEL_DEFCONFIG=qemu_x86

This line doesn't make sense, since the kernel does not have a
arch/x86/configs/qemu_x86_defconfig file. For x86, only two defconfigs
are available: i386 and x86_64.

> What steps did I miss? Is there a better/easier way to get from a clean buildroot to a working PXE setup?

Does PXE has anything to do with this? I think PXE just boots a kernel
+ optionally an initrd/initramfs, no?

Regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] Starting from scratch fails - how do I get to a basic PXE boot?

[Thomas Petazzoni]

Hello,

Le Fri, 13 Jul 2012 08:23:17 +0000,
"Bart J. Smit" <bart@smits.co.uk> a ?crit :

> I was under the impression from the on-line help that the BR2_LINUX_KERNEL_DEFCONFIG option had to specify one of the defconfig files from the configs directory. 

You're confusing two things:

 * The Buildroot defconfigs, which are stored in the configs/ directory
   of Buildroot. These defconfigs are *Buildroot* configuration for
   certain platforms.

 * The kernel defconfigs, which are part of the kernel sources, and
   available for each architecture in the arch/<ARCH>/configs/
   directory of the kernel source tree. This is the defconfig that is
   selected by BR2_LINUX_KERNEL_DEFCONFIG.

Now look at the available kernel defconfigs for x86:

$ ls arch/x86/configs/
i386_defconfig  x86_64_defconfig

So basically, on x86, for a vanilla Linux kernel, your only choice for
BR2_LINUX_KERNEL_DEFCONFIG is "i386", and for x86_64, your only choice
is "x86_64".

> It now builds without error, but booting the VM from the resulting bzImage and rootfs.cpio.gz causes it to stall at the same point as before. Could this be because I haven't cleaned the config? Any thoughts on how to wipe the slate clean? Will make clean do the trick?

'make clean' cleans up everything. The next 'make' invocation will
therefore restart the build from scratch completely.

If the thing halts at:

Starting logging: ON 
Initializing random number generator ... done.
Starting network ... 
[ 	2.227418] ip used greatest stack depth: 6392 bytes left

Then most likely the reason is that you have not properly configured
System configuration -> Port to run a getty (login prompt) on. You have
to figure out which serial port is used for the console of your
virtual machine, and set it in this configuration option.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com