Syslinux - Mar 2009 - [PATCH 0/3] v2: mbr: Ctrl-key press forces load from first hard disk

Version 2 of these patches includes optimisations suggested by H Peter
Alvin to save bytes:

  * Use memory-mapped I/O register to read keyboard shift flags
  * Don't reload DX from memory; move immediate byte to register

Tested using mbr.bin.

TJ (3):
  mbr: Ctrl-key press forces load from first hard disk
  gptmbr: Ctrl-key press forces load from first hard disk
  isohdpfx: Ctrl-key press forces load from first hard disk

 mbr/gptmbr.S   |   14 ++++++++++++--
 mbr/isohdpfx.S |   10 ++++++++++
 mbr/mbr.S      |   10 ++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

TJ wrote:
> Version 2 of these patches includes optimisations suggested by H Peter
> Alvin to save bytes:
> 
>   * Use memory-mapped I/O register to read keyboard shift flags
>   * Don't reload DX from memory; move immediate byte to register
> 
> Tested using mbr.bin.
> 
> TJ (3):
>   mbr: Ctrl-key press forces load from first hard disk
>   gptmbr: Ctrl-key press forces load from first hard disk
>   isohdpfx: Ctrl-key press forces load from first hard disk
> 
I did a slightly different version of the same idea which got the 
overhead down to 9 bytes and pushed that onto a new "ctrl-mbr" branch
of
the upstream git tree.

	-hpa

TJ wrote:
> Version 2 of these patches includes optimisations suggested by H Peter
> Alvin to save bytes:
>
>   * Use memory-mapped I/O register to read keyboard shift flags
>   * Don't reload DX from memory; move immediate byte to register
>
> Tested using mbr.bin.
>
> TJ (3):
>   mbr: Ctrl-key press forces load from first hard disk
>   gptmbr: Ctrl-key press forces load from first hard disk
>   isohdpfx: Ctrl-key press forces load from first hard disk
>
>  mbr/gptmbr.S   |   14 ++++++++++++--
>  mbr/isohdpfx.S |   10 ++++++++++
>  mbr/mbr.S      |   10 ++++++++++
>   
Is that possible to have a keyword in our configuration file to force
that mode ?

TJ wrote:
> Version 2 of these patches includes optimisations suggested by H Peter
> Alvin to save bytes:
>
>   * Use memory-mapped I/O register to read keyboard shift flags
>   * Don't reload DX from memory; move immediate byte to register
>
> Tested using mbr.bin.
>
> TJ (3):
>   mbr: Ctrl-key press forces load from first hard disk
>   gptmbr: Ctrl-key press forces load from first hard disk
>   isohdpfx: Ctrl-key press forces load from first hard disk
>   
This features sounds interesting and usefull but without any 
documentation, it might be forgotten by many of us.

Could you provide a patch for integrating some doc :
- What issue that patch is solving ?
- When do we use it ?
- How do we use it ?

Would be lovely in order not to let that patch get out of our memories :p

Cheers,
Erwan