Re: [Qemu-devel] [PATCH v15 00/10] ARM: Samsung Exynos4210-based boards support.

[Evgeny Voevodin <e.voevodin@samsung.com>]

On 15.02.2012 07:23, Evgeny Voevodin wrote:
> On 14.02.2012 23:51, Peter Maydell wrote:
>> On 10 February 2012 05:36, Evgeny Voevodin<e.voevodin@samsung.com> wrote:
>>> This set of patches adds support for Samsung Exynos4210-based boards
>>> NURI and SMDKC210.
>>> Tested on Linux kernel v3.x series.
>>> Boot smdkc210 board with root filesystem on NFS disk and serial port
>>> #0 redirected to terminal
>>> # qemu-system-arm -kernel ./zImage -append "console=ttySAC0,115200n8
>>> ip=dhcp root=/dev/nfs nfsroot=10.0.2.2:/srv/nfs/ rw " -serial stdio
>>> -M smdkc210
>> Have you tried booting this with the 'earlyprintk' kernel option?
>> I tried this with a 3.2.0 kernel and the exynos4 defconfig and it
>> crashes (without 'earlyprintk' is fine). What seems to be happening
>> is that the printk() in s3c_init_cpu() ends up taking an abort
>> trying to read the UART status register in the waituart macro.
>> This load has worked fine up until this point (with the same
>> address being used for the load) but I have a feeling this is the
>> first printk after we've done some fiddling with the memory mapping
>> of devices. Presumably without 'earlyprintk' we don't try to
>> do this output and will dump the whole printk buffer later via
>> a different codepath.
>>
>> Possibly this is a kernel bug but I'll let you track it down :-)
>>
>> -- PMM
>>
>
> Some times ago we have tried it but not recently. Will check it and
> report. Thanks.
>

My suggestion is that this is a kernel issue. Try latest 3.3-rc3. It 
works with "earlyprintk", though I can't see any valuable difference in 
output.

Also, make attention to what config says:

"Say Y here if you want the debug print routines to direct
their output to UART 0. The port must have been initialised
by the boot-loader before use."

We do not have appropriate bootloader, though 3.3-rc3 works without it.

-- 
Kind regards,
Evgeny Voevodin,
Leading Software Engineer,
ASWG, Moscow R&D center, Samsung Electronics
e-mail: e.voevodin@samsung.com