laurent.pinchart at skynet.be
Wed Apr 3 11:40:33 CST 2002
>>I need to implement the SharedUserData, which is a page of memory
>>located at (KERNEL_BASE - 0x10000) shared between user space (read-only
>>access) and kernel space.
>I don't know how to get the 'page fault' trap for a 'valid' user
>page on all systems that wine might run on. Certainly the assumption
>that (KERNEL_BASE - 0x10000) is available is probably false...
>However you don't actually need a valid user address, a kernel
>address (ie one that is always invalid) will do.
I'm not sure to understand what you mean. The user program will try to
access KERNEL_BASE - 0x10000 (which is 0x7ffe0000 on IA-32). I need that
to trigger a segfault.
>Catching SIGSEGV might be enough - but I'm not totally
>certain how you can get the value back into the main
>process context (emulate the instruction and modify the
>saved program counter ????)
That's what I thought at first. I could also try to set a hardware
breakpoint for read/write accesses at that address, but that's highly
not portable, and won't work nicely with a debugger. If someone has a
better idea I'll be glad to hear it.
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