RE: qemu hello world prints nothing..

[ckim]

Hello, Peter Maydell
Thank you so much again! I'll try your suggestions. Thanks!
Chan Kim

> -----Original Message-----
> From: Peter Maydell <peter.maydell@linaro.org>
> Sent: Tuesday, January 26, 2021 6:47 PM
> To: Chan Kim <ckim@etri.re.kr>
> Cc: qemu-discuss <qemu-discuss@nongnu.org>
> Subject: Re: qemu hello world prints nothing..
> 
> On Tue, 26 Jan 2021 at 07:02, <ckim@etri.re.kr> wrote:
> > I wish someone could help me here. Running a simple program on qemu is
> not easy for me.
> >
> > I tried to run baremetal hello world program and found this web page.
> >
> > (https://balau82.wordpress.com/2010/02/28/hello-world-for-bare-metal-a
> > rm-using-qemu/)
> >
> > This page is somewhat so old, but I decided to give it a try.
> [details of changes for aarch64 skipped]
> > When I execute
> >
> > “qemu-system-aarch64 -M virt -cpu cortex-a57 -kernel test.bin -nographic”
> >
> > nothing comes out.
> >
> > What can be wrong?
> 
> You tried to run a bare-metal program, and it isn't built correctly, so it
> has crashed. "Nothing happens" is the most common visible effect of a bug
> in initial startup of bare-metal programs. It's not specific to QEMU -- if
> you try to do bare metal development on real hardware you will see a lot
> of "nothing happened" there too.
> Now you have to debug it :-)
> 
> This is a good point to look into how to use gdb and connect it to the
> QEMU debug stub so that you can single step the initial startup of your
> program and see where it does something you don't expect it to.
> 
> As a more specific suggestion: the linker script in the tutorial is
> written for the 32-bit 'versatilepb' board, which has RAM starting at
> address 0. You're running on the aarch64 'virt' board, where address 0 has
> flash (ROM) memory, and RAM starts at 0x4000_0000. The UART also is not at
> the same address in 'virt'
> as it is in 'versatilepb'. You will need to adjust your linker script and
> the definition of UART0DR to work on the 'virt' board.
> 
> thanks
> -- PMM