Re: User-space to kernel communication
Re: User-space to kernel communication
- Subject: Re: User-space to kernel communication
- From: Greg <email@hidden>
- Date: Tue, 9 Jan 2007 22:40:18 -0500
On Jan 9, 2007, at 8:32 PM, Michael Smith wrote:
Also, as I asked in the other email, can you pass a pointer to a
user-land allocated buffer as a parameter to a method call for the
kernel to use?
You can, although the kernel can't access it directly. As I
pointed out previously, if the data is small (you mentioned 50
bytes, which is very small) you're better off just copying it. If
you need to pass it to hardware, or to map it, you need to
construct an IOMemoryDescriptor referencing it.
By "just copying it" do you mean, as Brian pointed out, passing a
structure of this sort:
typedef struct {
unsigned char buffer[256];
unsigned char bufferSize;
} MyIOUserClientArg;
Or do you mean that the kernel has read-access to user-allocated
memory (so that you could copy the data pointed to by a pointer).
Again, thank you for all your help so far, I really appreciate it.
- Greg
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