Re: [Qemu-devel] [PATCH v4 6/7] Make the kernel image in the fw_cfg DMA interface bootable

[Kevin O'Connor]

On Thu, Oct 01, 2015 at 05:25:11PM +0200, Laszlo Ersek wrote:
> On 10/01/15 14:16, Marc Marí wrote:
> > Add an entry to the bootorder file with name "vmlinux".
> > Give this entry more priority than the romfile.
> > 
> > Signed-off-by: Marc Marí <address@hidden>
> > ---
> >  hw/i386/pc.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 81d93b4..c4c51f7 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1012,8 +1012,10 @@ static void load_linux(PCMachineState *pcms,
> >      fw_cfg_add_bytes(fw_cfg, FW_CFG_SETUP_DATA, setup, setup_size);
> >  
> >      option_rom[nb_option_roms].name = "linuxboot.bin";
> > -    option_rom[nb_option_roms].bootindex = 0;
> > +    option_rom[nb_option_roms].bootindex = 1;
> >      nb_option_roms++;
> > +
> > +    add_boot_device_path(0, NULL, "vmlinux");
> >  }
> >  
> >  #define NE2000_NB_MAX 6
> > 
> 
> Where does this idea come from?
> 
> This will yet again break the invariant that the bootorder fw_cfg file
> is a list of OpenFirmware device paths.

I believe it came from a discussion between myself and Marc, because I
did not like the way Marc's original SeaBIOS patches overloaded the
meaning of "genroms/linuxboot.bin" in the bootorder file.

[...]
> Given that direct kernel boot is always expected to take priority over
> anything else (which is ensured by this QEMU patch too), can
> bootprio_find_vmlinux() in SeaBIOS just look at the same fw_cfg key
> (0x0008)?

That's fine with me.  Marc - I think qemu_vmlinux_setup() in SeaBIOS
with the following would work:

void qemu_vmlinux_setup(void)
{
    u32 kernel_size;
    qemu_cfg_read_entry(&kernel_size, QEMU_CFG_KERNEL_SIZE, 
sizeof(kernel_size));
    if (kernel_size)
        boot_add_qemu_vmlinux("QEMU Kernel image", 0);
}

Marc, if you're okay with the above, you don't have to keep respinning
patches - I can fix it up upon commit.

-Kevin