> On Oct 30, 2014, at 2:45 PM, Paulo Alcantara <[email protected]> wrote:
>
> OK. That would really clarify things a lot more. So, I am wondering where
> exactly such definitions and/or documentations should go?
>
> About the descriptions of UDF bridge and "conventional" UDF I would point out
> to the OSTA and ECMA specifications, as long as the latter I would expect
> more suggestions from the community.
>
>
OSTA and ECMA own the bits on the media, and how to boot from the media. But
the UEFI.og owns what order the platform does stuff in. Some of us also do the
UEFI.org UEFI spec thing too, so if we collect enough data from the mailing
list we can bring up an Engineering Change Request to get the UEFI spec
updated.
Thanks,
Andrew Fish
UEFI 2.4 spec:
12.3.2 Partition Discovery
This specification requires the firmware to be able to parse the legacy master
boot record(MBR) (see Section 5.2.1), GUID Partition Table (GPT)(see Section
5.3.2), and El Torito (see Section 12.3.2.1) logical device volumes. The EFI
firmware produces a logical EFI_BLOCK_IO_PROTOCOL device for:
Protocols - Media Access
• • •
each GUID Partition Entry (see table 16 in 5.3.3) with bit 1 set to zero;
each El Torito logical device volume; and
if no GPT is present, each partition found in the legacy MBR partition tables.
LBA zero of the EFI_BLOCK_IO_PROTOCOL device will correspond to the first
logical block of the partition. See Figure 30. If a GPT Partition Entry has
Attribute bit 1 set then a logical EFI_BLOCK_IO_PROTOCOL device must not be
created.
The following is the order in which a block device must be scanned to determine
if it contains partitions. When a check for a valid partitioning scheme
succeeds, the search terminates.
1. Check for GUID Partition Table Headers.
2. Follow ISO-9660 specification to search for ISO-9660 volume structures on
the magic LBA.
3. Check for an “El Torito” volume extension and follow the “El Torito” CD-ROM
specification.
4. If none of the above, check LBA 0 for a legacy MBR partition table.
5. No partition found on device.
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