分割为2GB:2GB而不是1GB:3GB时的linux内存映射 [英] linux memory mapping when the split is 2GB:2GB instead of 1GB:3GB
问题描述
当内核拥有2GB内存时会发生什么?
What happens when kernel owns 2GB of memory?
-
从3GB虚拟地址空间开始，894MB的直接映射将保持不变.
will the direct mapping of 894MB remains the same starting at 3GB of virtual address space.
将为vmalloc预留的临时映射将获得更多的128 MB虚拟内存，并再次获得低于3GB虚拟地址的新1GB. ?
will temporary mapping set aside for vmalloc gets more virtual memory that is 128 MB and again the new 1GB which is below the 3GB of the virtual address. ?
，适用于2GB内核空间.
is the below picture true for 2GB kernel space.
| ------------------ | 4GB
|------------------|4GB
| 128MB |
| 128MB |
vmalloc区域
| ------------------ |
|------------------|
| 896MB |
| 896MB |
| ---------------- | 3GB
|---------------- |3GB
| 1GB |
vmalloc区域
| ------------------- | 2GB
|-------------------|2GB
推荐答案
得到答案.
page_offset必须设置为0x80000000，而不是典型的默认值. 0xC0000000，这意味着所有高端内存区域都将映射到896MB内核内存之上.
The page_offset must be set to 0x80000000 instead of the typical default of 0xC0000000 ,which means all the high memory region will be mapped above the 896MB of kernel memory.
__ pa(x)和__va(x)使用此PAGE_OFFSET进行地址转换.
This PAGE_OFFSET is used by __pa(x) and __va(x) for address conversion.
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