Re: Proper support for PCI-based option rom loading (was Re: [Qemu-devel] Re: qdev property bug?)

[Gerd Hoffmann]

On 12/17/09 02:24, Kevin O'Connor wrote:
> On Wed, Dec 16, 2009 at 05:22:41PM +0100, Gerd Hoffmann wrote:
> The current "CBFS" mechanism looks for named "files" of the following
> form:
>
> - pciVVVV,DDDD.rom - a rom associated with a PCI device with the given
>    vendor and device id.

Might be useful for backward compatibility with older qemu versions as 
adding a rom bar to the pci devices is a guest-visible change in pci 
config space.

> - vgaroms/* - any "file" starting with the "vgaroms/" prefix is
>    treated as a vga option rom not associated with any specific pci
>    device.

obvious place for vgabios.

> - genroms/* - any "file" starting with the "genroms/" prefix is
>    treated as a generic option rom not associated with any specific pci
>    device.

and this for the non-pci roms like extboot &

> Associating a name to the fw_cfg entries and using the naming
> convention above would allow SeaBIOS to reuse its existing code.

Ok.

> > I'd tend to have one fw_cfg entry which returns structed data, like this:
> >
> > struct fw_files {
> >    u32 filecount;
> >    struct fw_file {
> >      u32  type;        /* vga, option, other? */
> >      u32  size;        /* file size */
> >      u32  select;      /* write this to 0x510 to read it */
> >      u32  reserved;    /* you never know ;) */
> >      char name[16];    /* maybe: filename */
> >    };
> > };
> >
> > What do you think?
>
> It works for me.  The name would need to be larger (64 bytes?).

I'd size name so it pads the struct to 32 or 64 bytes total.  32bit 
size, 16bit select, 16bit reserved, leaves 24 bytes for the name with 32 
bytes.  Hmm, better to go for a 64 byte struct, leaving 56 bytes for the 
name, which should be enougth.

I'll have patches ready later today.

cheers,
  Gerd