Re: [lwip-users] bug #17922 mem_malloc()

[Christiaan Simons]

Hi Jonathan,

> I've had a look. It looks fine from a reading.

Sure? I'm not, cause TCP seems to fail after these changes.

> Also I don't think we should
> handle near fits. Firstly, from the point of view of keeping it simple,
and
> secondly because I don't think you could sensibly handle them anyway
since
> you _always_ need to have an aligned struct mem following. A struct mem
is
> only three words after all.

I don't agree. First of all, the case Tom supplied may pass now,
but with a slight mod it will fail again.

Let say we change the last mem_malloc(200) into mem_malloc(195),
and this fails again without good reason.
Just because we can't create a mem2 is a bad reason to fail here.

I do think I should round up the requested size to span
to the next properly aligned struct.

I'm not sure if I must do this for each mem_malloc() call
or if I need to perform this trick only for the last free block,
which does complicate things.

Maybe this also explains the odd TCP errors I get.

> But I think there is a pre-existing problem - the ram array may only have

> byte alignment, but mem_init assigns a (struct mem *) to its base which
may
> have stronger alignment constraints.

Agreed. I'll have a look at it.

Bye,

Christiaan.

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