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?
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/Univer
sal/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_o
n_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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