Re: [Qemu-devel] Help needed to run Exynos 4210 linux kernel on qemu?

[Jean-Christophe DUBOIS]

Hello Igor,

Thanks for you reply and your time.

JC

On 09/05/2012 02:38 PM, Igor Mitsyanko wrote:
> On 09/04/2012 02:13 AM, Jean-Christophe DUBOIS wrote:
>
> Hello, Jean!
>
> I've just tried to do the same thing you're trying to do, it works for 
> me if I remove earlyprintk from append.

Yes, I found out about this in the mean time.

> Probably this is due to the fact that kernel expects uart0 to be 
> configured by u-boot prior to kernel start execution. Interestingly, 
> if you change default exynos4_defconfig CONFIG_DEBUG_S3C_UART0 to, for 
> example, CONFIG_DEBUG_S3C_UART2 in linux kernel configuration, 
> everything starting to work fine even with earlyprintk.

Seems strange. It would be nice if "earlyprintk" was not hanging though 
(is it possible to work around the actual LSP expectation?).

> But using ramdisks is always a pain for me, I would suggest you two 
> different approaches:

Ramdisk is fine for what I need to do at this time.

> 1) The most convenient way is to use emulated SD card for rootfs 
> storage. There is no SD card support for exynos4210 in current QEMU 
> master, but you can apply SD host controller patches I attached to 
> this email to get this support. These patches already have been 
> thoroughly reviewed in qemu-devel mailing list and hopefully would be 
> applied to QEMU master soon enough.
> If you want to use SD card instead of RAMDISK, apply these patches to 
> QEMU master with "git am", and enable MMC/SD support in linux kernel 
> configuration (it is disabled by default in exynos4_defconfig). You 
> need to check CONFIG_MMC, CONFIG_MMC_SDHC, CONFIG_MMC_SDHCI_S3C and 
> ONFIG_MMC_SDHCI_S3C_DMA.
> Then you can launch QEMU with -sd /path/to/your/rootfs and, for 
> example, append line -append "root=/dev/mmcblk0 rootfstype=ext4 rw 
> rootwait".

Thanks. That seems interesting but I don't need it right now. I can wait 
for this patch to hit mainline.

> 2) If you want to work only with what current QEMU master has, you can 
> use network filesystem as rootfs, but only for smdkc210 board (nuri 
> board doesn't have any net devices). You're gonna have to check these 
> options in Linux configuration:
> CONFIG_NET, CONFIG_PACKET, CONFIG_INET, CONFIG_IP_PNP, 
> CONFIG_IP_PNP_DHCP, CONFIG_NETDEVICES, CONFIG_SMSC911X, CONFIG_NFS_FS, 
> CONFIG_ROOT_NFS.
> Then, if, for example, you have directory /mnt/nfsroot exported by NFS 
> server on your host machine, you can launch QEMU guest with following 
> command line:
>
> qemu-system-arm -kernel ./zImage -M smdkc210 -append 
> "console=ttySAC0,115200n8 ip=dhcp root=/dev/nfs 
> nfsroot=10.0.2.2:/mnt/nfsroot/ rw" -serial stdio

Unfortunately, network will have to wait too. But it will come in a 
second step.

> Also, maybe you noticed, graphic support is disabled in 
> exynos4_defconfig by default. To enable it, check these options in 
> Linux configuration:
> CONFIG_DRM, CONFIG_DRM_EXYNOS, CONFIG_DRM_EXYNOS_DMABUF, 
> CONFIG_DRM_EXYNOS_FIMD. You can also check CONFIG_LOGO to get a fancy 
> penguins during guest VM startup. And if you need to start X server on 
> your guest VM, you also need to enable UNIX domain sockets in linux 
> kernel CONFIG_UNIX.

Thanks. I'll look at this later. No graphic is needed for now. A serial 
console is all I need.