Re: [HACKERS] patch for memory overrun on Linux(i386)

>
>Of course on x86 there is no special requirement any type to be aligned at
all.
>Double do not need to be 8 byte aligned. Ints do not need to be on an even
>address etc. So malloc can return a pointer to any address it wants on an
x86
>and still conform to the restriction.
Yes and I think it returns 4 byte aligned objects for performance reasons.
(This is more efficient than storing double/int on 1/2 byte boundaries.)

>
>On a Sparc or an Alpha, objects must to be aligned to the sizeof the type.
>So shorts are 2 byte aligned, ints 4 byte, and doubles 8 byte. Since malloc
>has no idea what you are allocating it has to return an 8 byte aligned
pointer.
>
>But all this is a bit of a red herring. The original bug if I recall was
>caused by the caller assuming that the return from palloc was 8 byte
aligned.
>Since the caller "knew" that the pointer was 8 byte aligned it then went on
>to do some "fancy" pointer arithmetic to arrive at an offset. This is what
>is broken, not the Linux malloc().
Yes, I think so too.
>
>That said, I have a plan in mind to get a nice performance boost for
palloc().
>As a side effect, I will guarantee 8 byte alignment of pointers returned
>from palloc().
>
Does this imply that more memory will be used that strictly necesary under
linux?

With regards from Maurice.