Messages in this thread | | | Date | Mon, 03 Aug 1998 16:41:33 +0000 | From | Christopher Eveland <> | Subject | Re: Problems with mmap |
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> I think you got the bigphysarea-2.1.85 patch from me:-) I'm glad > to hear that it works on 2.1.110 kernels. For those who do not > know, it is available at ftp://ftp.picturel.com/pub/source/, somewhere.
Ah, I was looking for it again, and didn't come up with it. Thanks for re-pointing me to it.
Anyway, the problem I was having turned out to actually be somewhat bigphysarea-related. In the earlier kernels, the pointer that bigphysarea_alloc returned was below PAGE_OFFSET (0xc0000000 in my case), while in 2.1.11X, it was above. Telling the hardware to DMA there seemes to work, but when I tell mmap where to map to I need to apply the __pa macro to it to get it to work.
What becomes clear here is that I don't quite understand all the different memory maps that exist in linux. Does anybody have a good source for (current) information on this, or willing to offer a short description of what I'm looking at?
One thing that changed between 2.1.85 and 2.1.11X, as far as I can tell, is at some of the static allocation of memory that happens in init/main.c. I'd like to make a bigphys-2.1.113 patch, and I've got a working system now, but I'd like to make sure its something close to the right working system.
Thanks for the help,
-Chris
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