> 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/pmap_quick_enter_page.9.md). # pmap\_quick\_enter\_page.9 `pmap_quick_enter_page` — 管理快速、单页面内核地址空间映射 ## 名称 `pmap_quick_enter_page`, `pmap_quick_remove_page` ## 概要 `#include ` `#include ` `#include ` `Ft vm_offset_t Fn pmap_quick_enter_page vm_page_t m Ft void Fn pmap_quick_remove_page vm_offset_t kva` ## 描述 `pmap_quick_enter_page` 函数接受单个页面 `m`，并将此页面输入到内核虚拟地址（KVA）空间中的预分配地址。此函数用于仅在非常短的时间内使用的临时映射，例如对页面内容的复制操作。 `pmap_quick_remove_page` 函数删除先前由 `pmap_quick_enter_page` 在 `kva` 处创建的映射，使 `pmap_quick_enter_page` 使用的 KVA 帧可供重用。 在许多架构上，`pmap_quick_enter_page` 使用每 CPU 页帧。在这些情况下，它必须禁用本地 CPU 上的抢占。然后，相应的 `pmap_quick_remove_page` 调用会重新启用抢占。因此，机器无关代码在持有这些映射时睡眠或执行锁定操作是不安全的。当前实现仅保证调用线程有单个页面可用，因此对 `pmap_quick_enter_page` 的调用不能嵌套。 `pmap_quick_enter_page` 和 `pmap_quick_remove_page` 不会睡眠，并且 `pmap_quick_enter_page` 始终返回有效地址。在除自旋互斥锁之外的所有类型的锁下使用这些函数是安全的。在除主中断上下文之外的所有线程上下文中使用它们也是安全的。 映射处于活动状态时，页面*不得*被交换或以其他方式重用。它必须被锁定或持有，或者必须属于非受管区域（如 I/O 设备内存）。 ## 返回值 `pmap_quick_enter_page` 函数返回映射到页面 `m` 的内核虚拟地址。 ## 参见 [pmap(9)](/man/man9/pmap.9.md) ## 作者 本手册页由 Jason A Harmening 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/pmap_quick_enter_page.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.