/proc/iomem的内容 [英] Content of /proc/iomem
问题描述
1)是否可以访问/proc/iomem中未定义的物理地址?
1) Is it possible to access a physical address which is not defined in /proc/iomem?
2)如果设备的物理地址范围未出现在/proc/iomem中，是否表示该设备尚未被使用/初始化?
2) If the physical address range of a device does not appear in /proc/iomem, does it mean that the device has not been utilized/initialized yet?
推荐答案
1)是否可以访问/proc/iomem中未定义的物理地址?
1) Is it possible to access a physical address which is not defined in /proc/iomem?
是的
假定内存映射所有直接连接的外围设备的ARM处理器，驱动程序可以执行ioremap()操作以将物理内存映射到虚拟内存以进行访问.
但是正确编写的驱动程序将首先调用request_mem_region()以确保其可以使用(并声明拥有)该物理地址空间.
/proc/iomem中的信息来自调用request_mem_region()的驱动程序.
Yes.
Assuming an ARM processor which memory maps all directly-connected periperals, the driver could perform an ioremap() operation to map the physical memory to virtual memory for access.
But a properly written driver would first call request_mem_region() to ensure that it can use (and lay claim to) that physical address space.
The information in /proc/iomem comes from drivers calling request_mem_region().
2)如果设备的物理地址范围未出现在/proc/iomem中，是否表示该设备尚未被使用/初始化?
2) If the physical address range of a device does not appear in /proc/iomem, does it mean that the device has not been utilized/initialized yet?
您必须检查驱动程序代码，以确定驱动程序的编写方式.
ioremap()之前是否有request_mem_region()?
使用dmesg命令检查系统日志；也许驱动程序初始化失败.
You would have to inspect the driver code to determine how well written the driver is.
Is there a request_mem_region() before the ioremap()?
Check the system log using the dmesg command; perhaps driver initialization failed.
假定这是一个静态链接的驱动程序，而不是可加载的模块，则由于每个内核设备驱动程序都有其init()例程，因此您可以通过在内核命令行上添加选项"initcall_debug"来获取跟踪输出.如果使用的是U-Boot，则应将此选项添加到"bootargs"变量(用于内核命令行).
Assuming that this is a statically-linked driver rather than a loadable module, then as each kernel device driver has its init() routine called you can get trace output by having added the option "initcall_debug" on the kernel command line. If you are using U-Boot, then this option should be added to the "bootargs" variable (which is used for the kernel command line).
这篇关于/proc/iomem的内容的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
