On 12/12/2025 at 17:29, Brian C. Lane wrote:
On Thu, Dec 11, 2025 at 09:44:39PM +0100, Pascal Hambourg wrote:
On 11/12/2025 at 20:51, Brian C. Lane wrote:
I'm not really comfortable with guessing at the
location of the primary partition array when using the backup header. It
would be better to use the backup table to try and search for the
primary, maybe?
Do you mean to search a correlation between the contents of the backup
partition entry array and of possible locations between the primary header
and the first usable LBA ?
Yes.
Then we need to a way to compare two partition entry arrays. Maybe
something like count the number of matching bytes, partition entries or
sectors ?
We'd have to assume that both tables aren't corrupt, which may not
be a great assumption considering this is triggered by the primary
header being invalid.
Other ideas welcome :)
The primary header is considered invalid if its partition entry array
CRC is wrong, even if the header CRC itself is good. I personally
disagree with this choice but this is per the UEFI/GPT specification.
So the disk may have an intact primary header (good header CRC) and a
damaged primary partition entry array (wrong partition entry array CRC).
In this case, couldn't its partition entry array LBA field be used ?
