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

[Marc Marí]

On Thu, 1 Oct 2015 12:02:42 -0400
"Kevin O'Connor" <address@hidden> wrote:

> 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.

I didn't like it either.

> [...]
> > 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.

I'm ok with it

Thanks
Marc