I am working on a Linux module for IA64. My current problem is that the driver uses the PAGE_SIZE and PAGE_SHIFT macros for dma page allocation. The problem I am having is that the machine compiling the driver is not the ones that needed to run the driver. So, if the PAGE_SIZE on the compiling machine is 2^14K and the destination machine is 2^16K then the driver fails.
I don't want to turn this question into a 'best practice' issue about compiling modules on machines which are not the ones running the modules. I understand the issues about that. What I found is that people mostly uses getpagesize() or sysconf(_SC_PAGE_SIZE). These two options are out of the ia64 kernel headers so I can't use them. Is there another way that I could get the runtime PAGE_SIZE?
Options I am looking at:
- Reading some file in /proc?
- syscall?
- Other function that let me calculate the PAGE_SIZE by inference (e.g ORDER, getpageshift, etc)?
- Other??
Answers;-
If you are trying to build a kernel module, you will need to have at least the kernel headers that are configured for the kernel the module will run on. Those will define the page size macros you need. If you don't have the correctly configured headers, the kernel will refuse to load your module.
And there is nothing wrong with compiling a module on one machine to run on another, even if it's a different architecture. You just need to build against the correct kernel source.
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