Anandtech published It Begins: AMD Announces Its First ARM Based Server SoC, 64-bit/8-core Opteron A1100 A quote from the article:

Around 15 months ago, AMD announced that it would be building 64-bit ARM based SoCs for servers in 2014. Less than a month into 2014, AMD made good on its promise and officially announced the Opteron A1100: a 64-bit ARM Cortex A57 based SoC. The Opteron A1100 features either 4 or 8 AMD Cortex A57 cores. There's only a single die mask so we're talking about harvested die to make up the quad-core configuration. My guess is over time we'll see that go away entirely, but since we're at very early stages of talking about the A1100 there's likely some hedging of bets going on.

 It Begins: AMD Announces Its First ARM Based Server SoC, 64-bit/8-core Opteron A1100 @ Anandtech