Re: question about a compressed Ffs3 file inside FFS2 filesystem

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

Yes. I think the challenge in the code is the compressed section is a guided section and the decompression is all handled transparently.  
One solution might be that once a section was processed that had attributes of EFI_GUIDED_SECTION_PROCESSING_REQUIRED then the check for filesystems should no longer be performed.  

Thanks
Sean


> -----Original Message-----
> From: afish@apple.com [mailto:afish@apple.com]
> Sent: Wednesday, October 19, 2016 4:40 PM
> To: Sean Brogan <sean.brogan@microsoft.com>
> Cc: edk2-devel@lists.01.org
> Subject: Re: [edk2] question about a compressed Ffs3 file inside FFS2
> filesystem
> 
> 
> > 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/
> Fw
> > Vol/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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