Re: question about a compressed Ffs3 file inside FFS2 filesystem

[Andrew Fish <afish@apple.com>]

> On Oct 19, 2016, at 4:09 PM, Sean Brogan <sean.brogan@microsoft.com> wrote:
> 
> 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?
> 

Sean,

If I understand correctly you are stating that the contents of an Encapsulation section should not have any restrictions on content type. The only error checking should be that the raw encapsulation section data needs to fit into the file type. That seems reasonable to me? I'm not sure if the PI spec makes some statement that the code is enforcing, or I guess the PI spec could be vague and people are interpreting it differently. 

Thanks,

Andrew Fish

> 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
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