[dpdk-dev] [dpdk-users] rte_zmalloc() returning non-zeroed memory on FreeBSD

[Thomas Monjalon]

Hi,

2016-08-10 23:30, Verkamp, Daniel:
> It seems that with DPDK 16.07, rte_zmalloc() and related functions no
> longer return zeroed memory reliably on FreeBSD.
> 
> I notice that commit b78c9175118f7d61022ddc5c62ce54a1bd73cea5 ("mem: do
> not zero out memory on zmalloc") removed the explicit memset() that used
> to ensure the buffer was zeroed; its log message says:
> 
> "Zeroing out memory on rte_zmalloc_socket is not required anymore since
> all allocated memory is already zeroed."

On Linux, the memory is zeroed by the kernel.
Then the zero value is maintained in the rte_malloc pool by rte_free.

> However, I don't see how this is guaranteed (at least for FreeBSD), and
> it is not true in practice.  I've attached a minimized reproducer program -
> running it twice in a row fails reliably for me.
> 
> Is there a missing step in FreeBSD, or is it a more general problem for
> other platforms?

I guess the initial value from the kernel has been verified only on Linux.
We could re-add a memset for FreeBSD.