On Oct 8, 2012, at 7:18 AM, Michael Lorer wrote:
> Hello Andrew,
>
> I have to correct myself. I mixed something up.
> I was able to find the GPT UniquePartitionGUID as part of the DevicePath.
> But I have to look for the Partition TYPE GUID and Attribute in
> GPT_PARTITION_ENTRY.
>
> But I’m just not able to build a correct ReadBlock()-Command to get the
> correct data.
> Any hints on that?
>
Look at the example code in the Partition driver.
> Thanks,
> Michael
>
> Von: Andrew Fish [mailto:af...@apple.com]
> Gesendet: Freitag, 5. Oktober 2012 16:51
> An: edk2-devel@lists.sourceforge.net
> Betreff: Re: [edk2] Get the GUIDs of all partitions out of the GPT
>
> What information are you trying to get? The GPT UniquePartitionGUID is
> discoverable from the DevicePath.
>
> The partition driver has created BlockIo protocol instances for each
> partition. So LBA 0 is the first LBA of the partition that start at LBA N on
> the disk. If you are looking for that BlockIo instance then you should be
> searching the device paths. That would be change your gBS->HandleProtocol
> (Handle[i], &gEfiBlockIoProtocolGuid, &BlockIo) over to
> gEfiDevicePathProtocolGuid and search the devices path for the
> UniquePartitionGUID.
>
> If you need to discover if a drive contains GPT and read the GPT header you
> should look at the algorithm in the partition driver. You can not assume that
> a BlockIo device contains GPT, it could be MBR, FAT, ISO-9660, ... A robust
> detection is a non trivial chunk of code, so you are better off using the
> device path if all you need to do is match GPT UniquePartitionGUID.
>
> Andrew Fish
>
> https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
>
> This is the code in the PartitionDriver, for GPT, that is building the device
> path node that will get appended to the physical BlockIo devices device path.
> This device path is placed on the handle that contains the BlockIo instance
> for the partition.
>
> EFI_PARTITION_ENTRY *Entry;
> HARDDRIVE_DEVICE_PATH HdDev;
> ZeroMem (&HdDev, sizeof (HdDev));
> HdDev.Header.Type = MEDIA_DEVICE_PATH;
> HdDev.Header.SubType = MEDIA_HARDDRIVE_DP;
> SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));
>
> HdDev.PartitionNumber = (UINT32) Index + 1;
> HdDev.MBRType = MBR_TYPE_EFI_PARTITION_TABLE_HEADER;
> HdDev.SignatureType = SIGNATURE_TYPE_GUID;
> HdDev.PartitionStart = Entry->StartingLBA;
> HdDev.PartitionSize = Entry->EndingLBA - Entry->StartingLBA + 1;
> CopyMem (HdDev.Signature, &Entry->UniquePartitionGUID, sizeof (EFI_GUID));
>
>
>
> On Oct 5, 2012, at 7:05 AM, Michael Lorer wrote:
>
>
> Hello,
>
> I’ve got a harddisk with a GPT and different partitions on it.
> Now I want to get the GUID of every partition (because I’m looking for a
> specific GUID).
>
> I tried it that way:
> // Get all BlockIO-protocols
> Status = gBS->LocateHandleBuffer(
> ByProtocol,
> &gEfiBlockIoProtocolGuid,
> NULL,
> &Count,
> &Handle);
>
> // Loop through it
> for( i=0; i<Count; i++ )
> {
> Status = gBS->HandleProtocol(Handle[i],
> &gEfiBlockIoProtocolGuid, &BlockIo);
>
> if (!BlockIo->Media->LogicalPartition)
> continue;
>
> Size=sizeof(GPT_HEADER);
> AdjustBufferSize(BlockIo, &Size);
>
> // Allocate memory to hold the data GPT header
> Status = gBS->AllocatePool(EfiBootServicesData, Size, &Gpt);
>
> // Read primary GPT
> BlockIo->ReadBlocks(BlockIo, BlockIo->Media->MediaId, 1,
> Size, Gpt);
>
> // Right now I should get a good value for
> Gpt->NumberOfPartitionEntries
> // but that is not the case.
> // In most cases Gpt->NumberOfPartitionEntries is empty and
> the only other value
> // is far too big to be the actual number of partitions
> // All other entries in the Gpt structure have the same
> disturbing values…
>
> }
>
> I had a look here:
> http://feishare.com/efimail/messages/20101023-0646-Re__edk2__Need_pointers_on_how_to_handle_GPT_disk_in_EDK2-Andrew_Fish.html
> And I think I’ve done it exactly as suggested. What am I missing?
>
> Thank you.
>
> Regards,
> Michael
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