[edk2] ConOut Protocol

Subject: [edk2] ConOut Protocol

From: Michael Chang <mchang@suse.com>

To: edk2-devel@lists.sourceforge.net

Date: 2012-06-01 23:58:14


In UEFI spec, it mentioned about the ConOut global UEFI variable is
the device path (EFI_DEVICE_PATH_PROTOCOL) of default output console,
but seems don't have description on ConOut protocol, which I could only
find on EFI 1.10 Driver Writer's Guide

"Driver #32 will install a ConOut device GUID on the handle if the
device path is listed in the ConOut global EFI variable ..."

"EFI uses these three protocols (ConIn, ConOut, and ErrOut) to mark
devices in the system, which have been selected by the user as ConIn,
ConOut, and StdErr. These protocols are actually just a GUID without
any services or data."

On my UEFI desktop "dh -p ConOut" reveals the handles.

I interested in this topic is becasue I want to leverage this protocol
to judge the correct handle if there are more than one handle provides
GOP protocol. For example, elilo simply picks the first located device
handle with GOP and use it, however in some circumstance it leads to a
garbled screen due to the handle is not associated with the real
physical output device.

But I am now afarid that since this protocol is not in specifcation,
it would not be mandatory for drivers to install it and may need to
figure out other way to circumvant it (or anyone has good suggestion
to judge the correct handle to use for GOP mode information during
boot? )


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