Re: [Xenomai-help] RTDM mmap alternative

[Rodrigo Rosenfeld Rosas <lbocseg@domain.hid>]

Hi Jan,

>...
>What precisely? I suggested to look at remap_pfn_range() or
>io_remap_page_range(). Do you see problems when using one of them?

This is the function prototype:

int remap_pfn_range(struct vm_area_struct *vma,
unsigned long virt_addr, unsigned long pfn,
unsigned long size, pgprot_t prot);

When a mmap call is issued, the vma structure is already initially filled. =
I=20
don't know how to fill it and LDD3 doesn't explain it:

"The arguments to remap_pfn_range are fairly straightforward, and most of t=
hem=20
are already provided to you in the VMA when your mmap method is called."

"Note that the kernel maintains lists and trees of VMAs to optimize area=20
lookup, and several fields of vm_area_struct are used to maintain this=20
organization. Therefore, VMAs can=E2=80=99t be created at will by a driver,=
 or the=20
structures break."

So, I don't know how to implement a mmap like ioctl. Any sugestions?

Thanks,

Rodrigo.

	

	
		
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