Add the ability to print an early hello message independent of debug
mask to the serial port when the firmware starts. Introduce a PCD entry
to set the message text (ArmPlatformPkg). If the message text is empty
(default) then nothing is printed.

The message is useful for debugging boot problems, especially with
silent firmware builds. It can take some seconds until the first line is
printed when booting the firmware, for example when running ArmVirt in
Qemu.

Use the above in ArmVirtPkg by defining a message text.

These changes have already been proposed by Laszlo Ersek in 2015.
I am reposting because I find this useful.


Example of a VM starting up, AARCH64, Qemu on X64). First line is the
new message. (Timestamp in seconds).

-VM start-
0000.094 | UEFI firmware starting.
00004.06 | BdsDxe: failed to load Boot0001 "UEFI Misc Device" from VenHw(93E34C7E-B50E-11DF-9223-2443DFD72085,00): Not Found
00004.08 | BdsDxe: loading Boot0002 "UEFI Misc Device 2" from PciRoot(0x0)/Pci(0x2,0x0)
00004.08 | BdsDxe: starting Boot0002 "UEFI Misc Device 2" from PciRoot(0x0)/Pci(0x2,0x0)
00004.11 | System BootOrder not found.  Initializing defaults.
00004.11 | Creating boot entry "Boot0005" with label "Red Hat Enterprise Linux" for file "\EFI\redhat\shimaa64.efi"
00004.15 |
00008.39 | EFI stub: Booting Linux Kernel...
[...]


PR: https://github.com/tianocore/edk2/pull/3140

Signed-off-by: Oliver Steffen <osteffen@redhat.com>

# Everything here is editable! You can modify the patch name, author,
# date, commit message, and the diff (if --diff was given).
# Lines starting with '#' will be ignored, and an empty message
# aborts the edit.

Laszlo Ersek (3):
  ArmPlatformPkg: introduce fixed PCD for early hello message
  ArmPlatformPkg: PrePeiCore: write early hello message to the serial
    port
  ArmVirtPkg: set early hello message

 ArmPlatformPkg/ArmPlatformPkg.dec               | 7 +++++++
 ArmVirtPkg/ArmVirtQemu.dsc                      | 1 +
 ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf  | 2 ++
 ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf | 2 ++
 ArmPlatformPkg/PrePeiCore/PrePeiCore.h          | 1 +
 ArmPlatformPkg/PrePeiCore/MainMPCore.c          | 5 +++++
 ArmPlatformPkg/PrePeiCore/MainUniCore.c         | 5 +++++
 7 files changed, 23 insertions(+)

-- 
2.37.1



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