芯片无法正常启动，系统日志出现如下打印信息：dev id 0, The address dont comply with the NVME protocol(must be aligned with 4KB).

问题描述

芯片无法正常启动时，系统日志有如下打印信息：dev id 0, The address dont comply with the NVME protocol(must be aligned with 4KB)。

可能原因

Host内核接口dma_alloc_coherent申请用于Nvme协议的地址不满足4K对齐要求。

根据内核DMA接口文档中相关描述，多数平台由于使用一致性内存代价很高，通常最小的分配长度为一个页。

Using Consistent DMA mappings
=============================

To allocate and map large (PAGE_SIZE or so) consistent DMA regions,
you should do::

	dma_addr_t dma_handle;

	cpu_addr = dma_alloc_coherent(dev, size, &dma_handle, gfp);

where device is a ``struct device *``. This may be called in interrupt
context with the GFP_ATOMIC flag.

Size is the length of the region you want to allocate, in bytes.

This routine will allocate RAM for that region, so it acts similarly to
__get_free_pages() (but takes size instead of a page order).  If your
driver needs regions sized smaller than a page, you may prefer using
the dma_pool interface, described below.

The consistent DMA mapping interfaces, will by default return a DMA address
which is 32-bit addressable.  Even if the device indicates (via the DMA mask)
that it may address the upper 32-bits, consistent allocation will only
return > 32-bit addresses for DMA if the consistent DMA mask has been
explicitly changed via dma_set_coherent_mask().  This is true of the
dma_pool interface as well.

dma_alloc_coherent() returns two values: the virtual address which you
can use to access it from the CPU and dma_handle which you pass to the
card.

The CPU virtual address and the DMA address are both
guaranteed to be aligned to the smallest PAGE_SIZE order which
is greater than or equal to the requested size.  This invariant
exists (for example) to guarantee that if you allocate a chunk
which is smaller than or equal to 64 kilobytes, the extent of the
buffer you receive will not cross a 64K boundary.

可能造成不满足4K对齐的原因如下：

• 用户内核PAGESIZE小于4096字节
• dma_alloc_coherent实现方式与Linux社区不一致

解决方案

1. 执行如下命令，查询该环境PAGESIZE。
   getconf PAGESIZE

   4096

   • 若PAGESIZE小于4096字节，请修改Host内核或修改PAGESIZE。
   • 若PAGESIZE大于4096字节，请排查Host内核接口dma_alloc_coherent申请一致性内存方式，确保申请的地址满足4K对齐。