> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man9/of_node_from_xref.9.md). # OF\_node\_from\_xref.9 `OF_node_from_xref` — 在内核 phandle 和有效 phandle 之间转换 ## 名称 `OF_node_from_xref`, `OF_xref_from_node` ## 概要 ```c #include #include phandle_t OF_node_from_xref(phandle_t xref) phandle_t OF_xref_from_node(phandle_t node) ``` ## 描述某些 OpenFirmware 实现（FDT、IBM）具有有效 phandle 或 xref 的概念。它们用于交叉引用设备树节点。例如，帧缓冲控制器可能引用控制背光的 GPIO 控制器和引脚。在此示例中，GPIO 节点将具有一个 cell（32 位整数）属性，其保留名称如 "phandle" 或 "linux,phandle"，其值唯一标识该节点。实际名称取决于实现。帧缓冲节点将具有一个由设备绑定（设备特定的属性集合）描述的名称的属性。它可以是 cell 属性，也可以是一个组合属性，其中一部分为 cell。帧缓冲节点属性的值将与 GPIO "phandle" 属性的值相同，因此可以说帧缓冲节点引用了 GPIO 节点。内核使用内部逻辑为设备树节点分配唯一标识符，这些值与 "phandle" 属性的值不匹配。`OF_node_from_xref` 和 `OF_xref_from_node` 用于在这两种节点标识符之间进行转换。 `OF_node_from_xref` 返回有效 phandle `xref` 对应的内核 phandle。如果找不到或 OpenFirmware 实现不支持有效 phandle，则函数返回输入值。 `OF_xref_from_node` 返回内核 phandle `node` 对应的有效 phandle。如果找不到或 OpenFirmware 实现不支持有效 phandle，则函数返回输入值。 ## 实例 ```c phandle_t panelnode, panelxref; char *model; if (OF_getencprop(node, "lcd-panel", &panelxref) <= 0) return; panelnode = OF_node_from_xref(panelxref); if (OF_getprop_alloc(hdminode, "model", (void **)&model) <= 0) return; ``` ## 参见 [OF\_device\_from\_xref(9)](/man/man9/of_device_from_xref.9.md), [OF\_device\_register\_xref(9)](/man/man9/of_device_from_xref.9.md) ## 作者本手册页由 Oleksandr Tymoshenko 编写。 --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://book.bsdcn.org/man/man9/of_node_from_xref.9.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.