[Qemu-devel] [PATCH] add "support" for enable/disable reverting to power-on defaults

[Carlo Marcelo Arenas Belon]

Greetings,

the following patch adds subcommands 0xCC and 0x66 for enabling/disabling
reverting to power-on defaults after a soft reset as invoked by the following
command (running under Linux) :

  # hdparm -K1 /dev/hda
  
  /dev/hda:
   setting drive keep features to 1 (on)

this is specially visible in OpenSolaris that locks the drive configuration 
at boot as shown by (line 1366):

  
http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/intel/io/dktp/controller/ata/ata_common.c

and therefore will complain with the following error when booted in qemu :

  ata_set_feature: (0x66,0x0) failed

the proposed implementation just ignores the flag but is consistent with the
current behavior for the other IDE feature flags (read look-ahead and write
cache) a complete implementation for all SET_FEATURES subcommands as spelled
in section 8.37 of the ATA/ATAPI 5 (T13/1321D revision 3) standard will be
provided later if the increase in complexity size is worth the added
functionality (to be debated)

Carlo

qemu-keep-features-over-reset.patch
Description: Text document