[syslinux] [RFC][PATCH] Gfxboot COMBOOT module

[Gene Cumm]

On Mon, Nov 24, 2008 at 1:40 AM, H. Peter Anvin <hpa at zytor.com> wrote:
> Gene Cumm wrote:
>>
>> Hmmm... gfxboot as a COMBOOT?  Sounds appealing.  Doesn't modify the
>> core yet allows the eye candy of gfxboot.  Seems like it should have
>> been this way from the beginning.
>>
>
> I'm rather confused, though, about the I/O stuff... does this attempt to
> read the filesystem itself?  That's hardly code we want to duplicate for
> the syslinux core.  Otherwise, why is pxelinux excluded?
>

As far as the duplicate code, I was noticing a few functions from
getc.inc (getc, ungetc, skipline).

It appears to use INT 22h AX=0006h,0007h,0008h to read the file.
Backing through the code, INT 22h AX=0019h (Read Disk) is called by
cb_readsector, which is referenced by cb_table, which is referenced by
gfx_cb, which is referenced by the data element gfx_callback which is
referenced by none.

Without looking at the original gfxboot patch, it would seem like
gfxboot did raw I/O but it is mearly a lingering reference.