The benefits of the DMA-like access method are (a) speed, (b) write
support in QEMU 2.9+.
(IOPort-based write support was discontinued in QEMU 2.4, and the
DMA-based one is being added to QEMU 2.9. Write support needs no separate
feature detection because writeability is governed on the level of
individual fw_cfg files -- if a file meant to be written by the firmware
exists in the directory, then it is writeable with the DMA method.)
We don't enable this feature for the SEC library instance, because:
- the SEC instance remains without clients (I've checked that it builds
though),
- in SEC, any possible fw_cfg use is expected to be small and read-only.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
InternalQemuFwCfgIsAvailable() is an API that is incorrectly exposed by
the "OvmfPkg/Include/Library/QemuFwCfgLib.h" library class header; the API
is meant to be used internally to library instances (if it's needed at
all).
In OvmfPkg, we have two lib instances (for SEC and PEI/DXE); they provide
different implementations of InternalQemuFwCfgIsAvailable(), for the
shared file "OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c". Move the API
declaration to a new internal header called "QemuFwCfgLibInternal.h", and
drop EFIAPI in the process.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Laszlo Ersek