Re: [Qemu-devel] HelloWord kernel for qemu-system-aarch64

[Claudio Fontana]

On 05.09.2014 16:50, Semion Prihodko wrote:
> Let's discard semihosting. I have aarch64-linux-gnu-* toolchain and
> qemu-system-aarch64 emulator. How can I build a minimal kernel which
> outputs Hello World! via serial port and run it on the emulator?
> 

If you run qemu with the "virt" platform, you can write to the UART at 0x9000000
to get a character out, works very early.

You could check the AArch64 port of the OSv Operating System, has a simple boot 
loader
you can look at (arch/aarch64/preboot.S and arch/aarch64/boot.S)
and the pl011 device you find in drivers/pl011.cc

https://github.com/cloudius-systems/osv/wiki/AArch64

Good luck,

Claudio

> 
> 2014-09-04 21:15 GMT+03:00 Christopher Covington <address@hidden>:
> 
>> Hi Semion,
>>
>> On 09/04/2014 09:40 AM, Semion Prihodko wrote:
>>> Still don't know how to build/run a simple Hello World kernel on
>>> qemu-system-aarch64?
>>>
>>> Guys, this is a very basic thing, please provide concrete steps. Thanks.
>>
>> Here you go. Start at the wget.
>>
>> http://lists.gnu.org/archive/html/qemu-devel/2014-07/msg03487.html
>>
>> Angel semihosting isn't implemented upstream so a text hello world won't be
>> trivial, although given enough time it should be possible to implement
>> Angel
>> semihosting for A64 in QEMU, implement DCC in QEMU and Newlib/libgloss or
>> implement PL011 UART or VirtIO-MMIO console in Newlib/libgloss.
>>
>> Some of the bootloaders and firmwares out there (bootwrapper, ARM trusted
>> firmware, UEFI/Tianocore) may have examples of using the PL011 UART.
>>
>> Christopher
>>
>> --
>> Employee of Qualcomm Innovation Center, Inc.
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> hosted by the Linux Foundation.
>>