AMBA总线是SoC设计中常用的一种总线，由ARM公司开发。根据ARM官网关于AMBA的总线介绍是一种开放协议（The ARM AMBA (Advanced Microcontroller Bus Architecture) protocol is an open standard, on-chip interconnect specification for the connection and management of functional blocks in a System-on-Chip (SoC). It facilitates right-first-time development of multi-processor designs with large numbers of controllers and peripherals. AMBA promotes design re-use by defining common interface standards for SoC modules.）。所以集成电路工程师一般认为使用AMBA总线不会有什么法律风险，但实际上AMBA的使用是由ARM以许可证的方式对外进行许可使用的，需要使用者满足许可证要求的条件才能获得许可，如果违反许可证的要求使用AMBA总线技术就可能造成法律风险。

我从官网上下载了AMBA® AXI Protocol Specification文档获取了AMBA SPECIFICATION LICENCE许可证，尝试逐条解读其中主要条款的要点，而不是逐字翻译。

原文

AMBA SPECIFICATION LICENCE

解读

这是AMBA 许可证的名称

原文

THIS END USER LICENCE AGREEMENT (“LICENCE”) IS A LEGAL AGREEMENT BETWEEN YOU (EITHER A SINGLE INDIVIDUAL, OR SINGLE LEGAL ENTITY) AND ARM LIMITED (“ARM”) FOR THE USE OF ARM’S INTELLECTUAL PROPERTY (INCLUDING, WITHOUT LIMITATION, ANY COPYRIGHT) IN THE RELEVANT AMBA SPECIFICATION ACCOMPANYING THIS LICENCE. ARM LICENSES THE RELEVANT AMBA SPECIFICATION TO YOU ON CONDITION THAT YOU ACCEPT ALL OF THE TERMS IN THIS LICENCE. BY CLICKING “I AGREE” OR OTHERWISE USING OR COPYING THE RELEVANT AMBA SPECIFICATION YOU INDICATE THAT YOU AGREE TO BE BOUND BY ALL THE TERMS OF THIS LICENCE.

解读：

这是一个关于使用ARM知识产权的最终用户许可协议，只要你使用或复制该规范就视为你同意受此许可证条款的约束。

原文

“LICENSEE” means You and your Subsidiaries. “Subsidiary” means, if You are a single entity, any company the majority of whose voting shares is now or hereafter owned or controlled, directly or indirectly, by You. A company shall be a Subsidiary only for the period during which such control exists.

解读：

对被许可人进行定义，这是英美合同的常规定义，大写LICENSEE表示特定概念，合同中使用大写的LICENSEE都是本句定义的含义。

原文

1. Subject to the provisions of Clauses 2, 3 and 4, Arm hereby grants to LICENSEE a perpetual, non-exclusive, non-transferable, royalty free, worldwide licence to:

(i) use and copy the relevant AMBA Specification for the purpose of developing and having developed products that comply with the relevant AMBA Specification;

(ii) manufacture and have manufactured products which either: (a) have been created by or for LICENSEE under the licence granted in Clause 1(i); or (b) incorporate a product(s) which has been created by a third party(s) under a licence granted by Arm in Clause 1(i) of such third party’s AMBA Specification Licence; and

 (iii) offer to sell, sell, supply or otherwise distribute products which have either been (a) created by or for LICENSEE under the licence granted in Clause 1(i); or (b) manufactured by or for LICENSEE under the licence granted in Clause 1(ii).

解释：

条款1规定只要遵守第2、3、4项条款的规定，Arm 就授权给被许可人一个永久、非排他、不可转让、免使用费、全球范围的许可可以做如下事情：为开发符合AMBA规范的产品而使用或复制该规范，或制造、销售、供应或发布上述产品。还可以采用第三方按本许可协议开发的产品。

原文

2. LICENSEE hereby agrees that the licence granted in Clause 1 is subject to the following restrictions: (i) where a product created under Clause 1(i) is an integrated circuit which includes a CPU then either: (a) such CPU shall only be manufactured under licence from Arm; or (b) such CPU is neither substantially compliant with nor marketed as being compliant with the Arm instruction sets licensed by Arm from time to time; (ii) the licences granted in Clause 1(iii) shall not extend to any portion or function of a product that is not itself compliant with part of the relevant AMBA Specification; and (iii) no right is granted to LICENSEE to sublicense the rights granted to LICENSEE under this Agreement.

条款2是获得许可的限制条件。

第(i)款限制如果条款1所开发的产品包括一个CPU。这个CPU要不就是从Arm获得许可，要不就是一个不与任何Arm指令集实质兼容、也不推销与Arm指令集兼容的CPU。该条款主要意图是排除兼容Arm指令集CPU使用AMBA总线的可能。

第(ii)款限制授予的许可不得扩展到产品本身不符合相关AMBA规范的任何部分或功能。所以魔改amba总线需要注意相关知识产权风险，增加的功能或部分要注意不侵犯Arm和第三方的知识产权。

第(iii)款限制被许可人再许可的权利，被许可人不能将获得的权利再许可给其他人，避免许可行为不受arm公司掌控。

其他许可条款我就不一一解释了，都是一般开源许可证常用条款，但要注意的是许可证第8条规定了许可证的管辖权适用英格兰法律。

后续条款原文如下：

3. Except as specifically licensed in accordance with Clause 1, LICENSEE acquires no right, title or interest in any Arm technology or any intellectual property embodied therein. In no event shall the licences granted in accordance with Clause 1 be construed as granting LICENSEE, expressly or by implication, estoppel or otherwise, a licence to use any Arm technology except the relevant AMBA Specification. 4. THE RELEVANT AMBA SPECIFICATION IS PROVIDED “AS IS” WITH NO REPRESENTATION OR WARRANTIES EXPRESS, IMPLIED OR STATUTORY, INCLUDING BUT NOT LIMITED TO ANY WARRANTY OF SATISFACTORY QUALITY, MERCHANTABILITY, NON-INFRINGEMENT OR FITNESS FOR A PARTICULAR PURPOSE, OR THAT ANY USE OR IMPLEMENTATION OF SUCH ARM TECHNOLOGY WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADE SECRETS OR OTHER INTELLECTUAL PROPERTY RIGHTS. 5. NOTWITHSTANDING ANYTHING TO THE CONTRARY CONTAINED IN THIS AGREEMENT, TO THE FULLEST EXTENT PETMITTED BY LAW, THE MAXIMUM LIABILITY OF ARM IN AGGREGATE FOR ALL CLAIMS MADE AGAINST ARM, IN CONTRACT, TORT OR OTHERWISE, IN CONNECTION WITH THE SUBJECT MATTER OF THIS AGREEMENT (INCLUDING WITHOUT LIMITATION (I) LICENSEE’S USE OF THE ARM TECHNOLOGY; AND (II) THE IMPLEMENTATION OF THE ARM TECHNOLOGY IN ANY PRODUCT CREATED BY LICENSEE UNDER THIS AGREEMENT) SHALL NOT EXCEED THE FEES PAID (IF ANY) BY LICENSEE TO ARM UNDER THIS AGREEMENT. THE EXISTENCE OF MORE THAN ONE CLAIM OR SUIT WILL NOT ENLARGE OR EXTEND THE LIMIT. LICENSEE RELEASES ARM FROM ALL OBLIGATIONS, LIABILITY, CLAIMS OR DEMANDS IN EXCESS OF THIS LIMITATION.

6. No licence, express, implied or otherwise, is granted to LICENSEE, under the provisions of Clause 1, to use the Arm tradename, or AMBA trademark in connection with the relevant AMBA Specification or any products based thereon. Nothing in Clause 1 shall be construed as authority for LICENSEE to make any representations on behalf of Arm in respect of the relevant AMBA Specification. 7. This Licence shall remain in force until terminated by you or by Arm. Without prejudice to any of its other rights if LICENSEE is in breach of any of the terms and conditions of this Licence then Arm may terminate this Licence immediately upon giving written notice to You. You may terminate this Licence at any time. Upon expiry or termination of this Licence by You or by Arm LICENSEE shall stop using the relevant AMBA Specification and destroy all copies of the relevant AMBA Specification in your possession together with all documentation and related materials. Upon expiry or termination of this Licence, the provisions of clauses 6 and 7 shall survive. 8. The validity, construction and performance of this Agreement shall be governed by English Law.