OvmfPkg: BDS: don't overwrite the BDS Front Page timeout
The PlatformBdsEnterFrontPage() function's first parameter,
"TimeoutDefault", determines the behavior of the setup utility:
- If (TimeoutDefault == 0), then the usual boot order is to be acted upon
immediately.
- If (TimeoutDefault == 0xFFFF), then the setup utility is entered
unconditionally.
- If (0 < TimeoutDefault && TimeoutDefault < 0xFFFF), then the
PlatformBdsEnterFrontPage() function displays a progress bar, waiting
for TimeoutDefault seconds. If the user presses a key, then the setup
utility is entered, otherwise the normal boot option processing takes
place.
The TimeoutDefault parameter is supposed to be set from
gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdPlatformBootTimeOut
which has the following (matching) documentation in
"IntelFrameworkModulePkg/IntelFrameworkModulePkg.dec":
The number of seconds that the firmware will wait before initiating the
original default boot selection.
A value of 0 indicates that the default boot selection is to be
initiated immediately on boot.
The value of 0xFFFF then firmware will wait for user input before
booting.
OVMF does this actually -- see the Timeout variable in
PlatformBdsPolicyBehavior() -- but right before calling
PlatformBdsEnterFrontPage(), OVMF hardwires TimeoutDefault to 0xFFFF.
This has been acceptable until now, because OVMF implements its own "wait
for keypress at the splash screen" logic in PlatformBdsPolicyBehavior(),
completely avoiding the progress bar mentioned above. OVMF only calls
PlatformBdsEnterFrontPage() when the user presses a key during its own
"splash screen wait", and *then* it indeed makes sense to enter the setup
utility unconditionally.
However, even that way, the
Timeout = 0xffff;
assignment is superfluous, because 0xFFFF is already the default value of
PcdPlatformBootTimeOut in "IntelFrameworkModulePkg.dec", and OvmfPkg
doesn't override it in its DSC files.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16307 6f19259b-4bc3-4df7-8a09-765794883524
1 file changed