Re: [dpdk-dev] [PATCH v1] devtools: update abi ignore for cryptodev

[Dodji Seketeli <dodji@redhat.com>]

Thomas Monjalon <thomas@monjalon.net> writes:

[...]

>> > Then I've added (quickly) a libabigail exception rule:
>> >
>> > [suppress_type]
>> > 	name = rte_cryptodev
>> > 	has_data_member_inserted_between = {0, 1023}
>> >
>> > Now we want to improve this rule to restrict the offsets
>> > to the padding at the end of the struct only,
>> > so we keep forbidding changes in existing fields,
>> > and forbidding additions further the current struct size.
>> > Is this new rule good?
>> >
>> > 	has_data_member_inserted_between = {offset_after(attached), end}
>> 
>> 
>> Yes, this rule should do what you think it says.
>> 
>> > Do you confirm that the keyword "end" means the old reference size?
>> 
>> Yes I do.
>> 
>> 
>> > What else do we need to check for adding a new field in a padding?
>> 
>> Actually, that rule will work independantly of it there is enough
>> padding or not.  It'll shut down the change report, even if the added
>> data exceeds the padding.
>
> I don't understand why.
> If "end" means the old reference size, then addition after the old size
> should be reported, isn't it?

Yes, you are right.

What I meant is that even if (in an hypothetical case, not yours) the
padding was so "small" that it wasn't going up to the 'end' of the
struct, that rule would have still shut down the change report.

[...]

Cheers,

-- 
		Dodji