question about a compressed Ffs3 file inside FFS2 filesystem

[Sean Brogan <sean.brogan@microsoft.com>]

We have a condition that occurs when we boot where we see the following message and our boot fails because of it.
DEBUG ((EFI_D_ERROR, "Found a FFS3 formatted section in a non-FFS3 formatted FV.\n"));

Which is on line 773 of FwVol.c ( https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Pei/FwVol/FwVol.c )

The condition is caused by a large firmware volume (greater than 16mb) that is compressed and put into a smaller FV (less than 16mb).  My question is why isn't this allowed (seems like a valid scenario).  Volinfo supports this and decodes binary fine.  The PI Vol 3 spec has a section 3.2.2  EFI_FIRMWARE_FILE_SYSTEM3_GUID which says FileSystem2 doesn't support large files but it seems that the code is not taking into account that the section is compressed and therefore you can have a large file inside a compressed section inside a FV with File System2.

Feedback/thoughts/comments/Bug?

Here are some details of my scenario.
Compressed FV has filesystem == 8c8ce578-8a3d-4f1c-9935-896185c32dd3  (ffs3)
Non compressed FV has filesystem == 5473c07a-3dcb-4dca-bd6f-1e9689e7349a (ffs2)

VolInfo dump of the Non Compressed FV showing the nested/compressed FV inside.

Decoding
VolInfo Version 1.0 Build Build 20909
Signature:        _FVH (4856465F)
Attributes:       4FEFF
       EFI_FVB2_READ_DISABLED_CAP
       EFI_FVB2_READ_ENABLED_CAP
       EFI_FVB2_READ_STATUS
       EFI_FVB2_WRITE_DISABLED_CAP
       EFI_FVB2_WRITE_ENABLED_CAP
       EFI_FVB2_WRITE_STATUS
       EFI_FVB2_LOCK_CAP
       EFI_FVB2_LOCK_STATUS
       EFI_FVB2_STICKY_WRITE
       EFI_FVB2_MEMORY_MAPPED
       EFI_FVB2_ERASE_POLARITY
       EFI_FVB2_READ_LOCK_CAP
       EFI_FVB2_READ_LOCK_STATUS
       EFI_FVB2_WRITE_LOCK_CAP
       EFI_FVB2_WRITE_LOCK_STATUS
        EFI_FVB2_ALIGNMENT_16
        EFI_FVB2_ALIGNMENT_32
        EFI_FVB2_ALIGNMENT_64
        EFI_FVB2_ALIGNMENT_128
        EFI_FVB2_ALIGNMENT_4K
        EFI_FVB2_ALIGNMENT_8K
        EFI_FVB2_ALIGNMENT_16K
        EFI_FVB2_ALIGNMENT_32K
        EFI_FVB2_ALIGNMENT_1M
        EFI_FVB2_ALIGNMENT_2M
       EFI_FVB2_ALIGNMENT_4M
        EFI_FVB2_ALIGNMENT_8M
        EFI_FVB2_ALIGNMENT_256M
        EFI_FVB2_ALIGNMENT_512M
        EFI_FVB2_ALIGNMENT_1G
        EFI_FVB2_ALIGNMENT_2G
Header Length:         0x00000048
File System ID:        5473c07a-3dcb-4dca-bd6f-1e9689e7349a
Revision:              0x0002
Number of Blocks:      0x00000028
Block Length:          0x00010000
Total Volume Size:     0x00280000
============================================================
File Name:        9E21FD93-9C72-4C15-8C4B-E77F1DB2D792
File Offset:      0x00000048
File Length:      0x001F3FFD
File Attributes:  0x00
File State:       0xF8
        EFI_FILE_DATA_VALID
File Type:        0x0B  EFI_FV_FILETYPE_FIRMWARE_VOLUME_IMAGE
------------------------------------------------------------
  Type:  EFI_SECTION_GUID_DEFINED
  Size:  0x001F3FE5
  SectionDefinitionGuid:  ee4e5898-3914-4259-9d6e-dc7bd79403cf

  DataOffset:             0x0018
  Attributes:             0x0001
------------------------------------------------------------
  Type:  EFI_SECTION_RAW
  Size:  0x00000FF8
------------------------------------------------------------
  Type:  EFI_SECTION_FIRMWARE_VOLUME_IMAGE
  Size:  0x01010008
============================================================

Thanks
Sean