Re: [Qemu-devel] versatilepb cannot load roofs

[Peter Maydell <peter.maydell@linaro.org>]

On 5 March 2017 at 07:57, Jiahuan Zhang <jiahuanzhang90@gmail.com> wrote:
> Dear QEMU developers,
>
> I have a problem when running qemu to build a system with versatilepb,
> linux zImage and rootfs. the qemu cmdl is as follows.
>
> ../qemu/build/arm-softmmu/qemu-system-arm.exe -M versatilepb -kernel zImage
> -dtb versatile-pb.dtb -initrd ramfs.gz -nographic -append "console=ttyAMA0
> root=/dev/ram0"
>
> However, the running result is the same as the case without the initrd
> file, which is "Kernel panic - not syncing: VFS: Unable to mount root fs on
> unknown-block(1,0)".
>
> The kernel is configured with versatile_defconfig, ramfs.gz is created by
> busybox 1.25.1. I am using QEMU 2.8.50 and Linux 4.7. I've also tried with
> Linux 2.6.35 and 3.2.8, and still versatilepb gives this kernel panic.

> No filesystem could mount root, tried:  ext2 cramfs minix romfs
> Kernel panic - not syncing: VFS: Unable to mount root fs on
> unknown-block(1,0)


This is a guest configuration error, not a QEMU bug. The kernel
message means "I found the root device, but I did not recognize
its contents as one of the above filesystem types". Probably
the thing you are trying to use as an initrd is something
like a compressed cpio archive, not an actual filesystem that
you can pass to root=. You need to either fix what you're using
to create the initrd or you need to fix the kernel command line
so you don't try to use it as a root device. (Usually an initrd
isn't the root= device, unless you've constructed it specially
for that purpose.)

thanks
-- PMM