[U-Boot] [PATCH v2 28/29] riscv: qemu: detect and boot the kernel passed by QEMU

[Auer, Lukas]

Hi Bin,

On Sun, 2018-11-04 at 22:39 +0800, Bin Meng wrote:
> Hi Lukas,
> 
> On Tue, Oct 30, 2018 at 8:57 PM Lukas Auer
> <lukas.auer at aisec.fraunhofer.de> wrote:
> > 
> > QEMU embeds the location of the kernel image in the device tree.
> > Store
> > this address in the environment as variable kernel_start and use it
> > in
> > CONFIG_BOOTCOMMAND to boot the kernel. Use the device tree passed
> > by the
> > prior boot stage to boot Linux.
> > 
> > Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
> > ---
> > 
> > Changes in v2:
> > - Rebase onto u-boot-dm/next
> > - Boot Linux with the device tree provided by the prior boot stage
> > 
> >  board/emulation/qemu-riscv/Kconfig      |  1 +
> >  board/emulation/qemu-riscv/qemu-riscv.c | 29
> > +++++++++++++++++++++++++
> >  configs/qemu-riscv32_defconfig          |  1 +
> >  configs/qemu-riscv64_defconfig          |  1 +
> >  include/configs/qemu-riscv.h            | 10 ++++++++-
> >  5 files changed, 41 insertions(+), 1 deletion(-)
> > 
> > diff --git a/board/emulation/qemu-riscv/Kconfig
> > b/board/emulation/qemu-riscv/Kconfig
> > index 37a80db6a9..be5839b7db 100644
> > --- a/board/emulation/qemu-riscv/Kconfig
> > +++ b/board/emulation/qemu-riscv/Kconfig
> > @@ -29,5 +29,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
> >         imply CMD_EXT2
> >         imply CMD_EXT4
> >         imply CMD_FAT
> > +       imply BOARD_LATE_INIT
> > 
> >  endif
> > diff --git a/board/emulation/qemu-riscv/qemu-riscv.c
> > b/board/emulation/qemu-riscv/qemu-riscv.c
> > index 2ce093e19a..ee20983095 100644
> > --- a/board/emulation/qemu-riscv/qemu-riscv.c
> > +++ b/board/emulation/qemu-riscv/qemu-riscv.c
> > @@ -19,3 +19,32 @@ int board_init(void)
> > 
> >         return 0;
> >  }
> > +
> > +int board_late_init(void)
> > +{
> > +       ulong kernel_start;
> > +       ofnode chosen_node;
> > +       int ret;
> > +
> > +       chosen_node = ofnode_path("/chosen");
> > +       if (!ofnode_valid(chosen_node)) {
> > +               printf("No chosen node found\n");
> > +               return 0;
> > +       }
> > +
> > +#ifdef CONFIG_ARCH_RV64I
> > +       ret = ofnode_read_u64(chosen_node, "riscv,kernel-start",
> > +                             (u64 *)&kernel_start);
> > +#else
> > +       ret = ofnode_read_u32(chosen_node, "riscv,kernel-start",
> > +                             (u32 *)&kernel_start);
> > +#endif
> > +       if (ret) {
> > +               printf("Can't find kernel start address in device
> > tree\n");
> 
> I think we need use 'debug' instead of 'printf' here, for situation
> that kernel is not passed to QEMU.
> 

Yes, you are right. What is the current best-practice here? Should I
use one of the pr_* functions or just debug?

Looking at the function, I am also not sure how useful the printf above
is (no chosen node found). I could replace it with the same text as in
the last printf. What do you think?

Thanks,
Lukas

> > +               return 0;
> > +       }
> > +
> > +       env_set_hex("kernel_start", kernel_start);
> > +
> > +       return 0;
> > +}
> 
> [snip]
> 
> Regards,
> Bin