Re: [Question] Can I start qemu-system-aarch64 with a vmlinux(ELF format)?

[Kunkun Jiang]

Hi Peter，

On 2024/2/29 17:44, Peter Maydell wrote:
> On Thu, 29 Feb 2024 at 03:01, Kunkun Jiang <jiangkunkun@huawei.com> wrote:
> > Hi Peter,
> >
> > On 2024/2/27 23:28, Peter Maydell wrote:
> > > On Tue, 27 Feb 2024 at 14:42, Kunkun Jiang via <qemu-devel@nongnu.org> wrote:
> > > > Hi everybody,
> > > >
> > > > I want to start qemu-system-aarch64 with a vmlinux,
> > > > which is an ELF format file. The arm_load_elf() is
> > > > implemented in arm_setup_direct_kernel_boot(). So I
> > > > thought it was supporting the ELF format file.
> > > No, you can't do this. The hw/arm/boot.c code assumes
> > > that ELF files are "bare metal" binaries, whereas
> > > uImage format, AArch64 Image format, and raw binary files
> > > are Linux kernels. Only the last three kinds of files will
> > > be started with the boot protocol the Linux kernel expects.
> > >
> > > For AArch64, pass the -kernel option the path to the Image
> > > file, not the vmlinux file.
> > Yes, it works fine using Image files.
> > I would also like to ask again, is it because AArch64 does not
> > support vmlinux, or is it because qemu does not implement
> > this capability?
> As I said, it is because QEMU assumes that ELF files are
> bare metal images, not Linux kernel images.

Sorry to bother you again. I still have a few questions.
1. What does "bare metal images" mean? Are they used in tcg mode?

2. How QEMU assumes an ELF file is a bare metal image? Can you post
the corresponding code?

3. How can I make the hw/arm/boot.c code assumes the ELF files are
Linux kernels?

Looking forward to your reply.

Thanks,
Kunkun Jiang