Re: [Qemu-devel] Re: [PATCH][SEABIOS] Move qemu config port access functions into separate file.

[Gleb Natapov]

On Wed, Sep 30, 2009 at 08:17:26PM +0300, Blue Swirl wrote:
> On Wed, Sep 30, 2009 at 9:35 AM, Gleb Natapov <address@hidden> wrote:
> > On Tue, Sep 29, 2009 at 09:09:46PM -0400, Kevin O'Connor wrote:
> >> On Sat, Sep 19, 2009 at 08:56:55PM +0300, Gleb Natapov wrote:
> >> > On Sat, Sep 19, 2009 at 11:16:41AM -0400, Kevin O'Connor wrote:
> >> > > Maybe a stream could be introduced with something like:
> >> > > <name><len><data> <name2><len2><data2> ...
> >> > >
> >> > The format is already set. The are two ports. You write option id in
> >> > first port and you read option value from second one. The value format
> >> > is different for each option. Additional acpi table format is like I
> >> > described above. If we want to use the same APIs for config access for
> >> > coreboot and qemu the API will have to be general enough to accommodate
> >> > both approaches. Changing formats is not an option at this stage.
> >>
> >> Okay - it doesn't sound like there is much overlap here between qemu
> >> and coreboot.  On coreboot cbfs is used for pulling out option roms,
> >> executables, and floppy images - none of which have much use under
> >> qemu anyway.
> >>
> >> So, maybe we should just go back to the discussion of a config
> >> interface.  I think it would be nice to have one api for getting
> >> config items for both qemu and coreboot - something like
> >> get_config_u32("ShowBootMenu").  On coreboot that info could then be
> >> extracted from cbfs and qemu can get in from the "cfg port".
> >>
> >> Does that make sense?
> >>
> > Yes. That is the direction I was going to take. Lest implement simple
> > name/value interface first and table loading code will be different.
> > If there will be much overlap in table loading code we will unify it
> > later.
> 
> The name/value interface could be useful for OpenBIOS too if we want
> to avoid using NVRAM for OpenBIOS variables for compatibility. There
> should be methods to iterate through all keys and get the byte size of
> the value.
> 
> For example, current fw_cfg interface could be extended to allow
> string keys in addition to integer keys.
There are two types of string keys. Those that you know the length in
advance (like uuid) and those you don't. fw_cfg can support second type
without additional change by passing <len><string> as a value. This will
be hidden from seabios behind get_config_string() interface of course.

--
                        Gleb.