If you have constructed the call properly the 1st thing to look at is the UEFI
spec as it usually calls out error returns for protocol member functions.
So for example EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume() has this text:
If the medium is changed while there are open file handles to the volume, all
file handles to the volume will return EFI_MEDIA_CHANGED. To access the files
on the new medium, the volume must be reopened with OpenVolume(). If the new
medium is a different file system than the one supplied in the EFI_HANDLE’s
DevicePath for the EFI_SIMPLE_SYSTEM_PROTOCOL, OpenVolume() will return
EFI_UNSUPPORTED.
Passing the wrong arguments to the protocol member functions is also a common
error.
Andrew Fish
On Sep 11, 2012, at 10:11 AM, Bhavana Brar wrote:
> Thanks Andrew for the information. This does clarify my questions quite a
> bit.
> Currently when I try and open the SimpleFileSystem protocol within my test
> application , I get the error - unsupported. At this point, I'm just
> experimenting with opening text files within the FAT32 partition itself in
> which the efi application resides.
>
> Any idea on what I may be doing wrong ?
>
>
>
> From: Andrew Fish <[email protected]>
> To: [email protected]
> Date: 09/11/2012 09:46 AM
> Subject: Re: [edk2] EFI app access files on a non FAT partition
>
>
>
> Not sure what you are asking?
>
> The edk2 has a partition driver that speaks MBR (PC Master Boot Record), GPT
> (as defined in UEFI), an El Torito for CD-ROM (not ISO-9660). A file system
> driver can then just sit on top of the Block IO produced by the partition
> driver, so the file system driver is not aware of partitioning.
>
> To access a non-FAT file system you need an EFI driver the produces the
> Simple File System Protocol on top of BlockIo, and usually DiskIo.
>
> There are no security restrictions on what an EFI application can access.
>
> An application can figure out where it was loaded from by looking into the
> Loaded Image protocol instanced installed on the ImageHandle. This is the
> same ImageHandle that is passed into the entry point of the image.
>
>
> Andrew Fish
>
>
>
> On Sep 10, 2012, at 11:21 AM, Bhavana Brar wrote:
>
> Hi,
> Can an EFI app residing in a FAT32 partition access a file ( for read/write)
> that exists on a non FAT partition?
> Thanks!------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats.
> http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/_______________________________________________
> edk2-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/edk2-devel
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats.
> http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/_______________________________________________
> edk2-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/edk2-devel
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats.
> http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/_______________________________________________
> edk2-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/edk2-devel
------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and
threat landscape has changed and how IT managers can respond. Discussions
will include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
edk2-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/edk2-devel
