Messages in this thread | | | Subject | Re: Faking a memory map? | From | Jeremy Jackson <> | Date | 13 Feb 2003 13:14:52 -0500 |
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On Tue, 2003-02-11 at 19:21, David Frascone wrote: > I'm trying to get an existing SDK (userland) for a PCI hardware device > to work across a different propriatary bit-banged interface. > > The original device driver just mmaped the PCI registers / address > space into userland. (talk about lazy ;) > > Anyway, the hardware I'm working with is *not* on the PCI bus, and > therefore not memory-mappable. So, I'm stuck with a complex driver > design (compared to the original), and rewriting the entire bottom of > the SDK. > > So, I thought: Is there a way to cheat? Would it be possible for me > to *fake* the SDK out by memory mapping some RAM, and then reading / > writing to the ram after bit-banging the device. > > I looked into it some, but I couldn't figure out how to get notified > when the region was read/written to (only when the page changed). So, > is it possible to do the (admitedly ugly) hack I'm attempting?
I think you would have to use mprotect(,,PROT_NONE), set the region to disallow read/write, and then each SEGV would have to be decoded, and the trap told to continue as though the access did take place.
Take a look at the mprotect man page for an example, and then sigaction arount the siginfo_t area. in siginfo_t.si_addr it gives the address that faulted. > > Thanks in advance, > > -Dave -- Jeremy Jackson <jerj@coplanar.net>
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