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.
