From: Ilan Finci (ifinci_at_nonexisting.hamakor.org.il)
Date: Sun 30 Jan 2005 - 18:08:53 IST
Thanks all for the help.
I've tried before to replace the MAP_PRIVATE to MAP_SHARED, but then the
memory is mapped to 0xffffffff, and accessing the memory address later
fails with segmentation fault (since when I add 0x24, it yields a
pointer to 0x00000023)
Using the nopage operation, go me to no better results.
Ilan
on 01/30/05 16:50 Gilad Ben-Yossef said the following:
> Ilan Finci wrote:
>
>
>> Calling mmap from the user application returns an address, but trying
>> to access this address, yields an error message:
>>
>> do_wp_page: bogus page at address 30027024 (page 0xc23358e0)
>> VM: killing process testSram
>>
>>
>> (0x30027000 is the address that mmap returned, and I tried to access
>> 24 bytes after this. I've mapped 0x40000 bytes, so there shouldn't be
>> a problem).
>>
>
> In the flags to the mmap call replace MAP_PRIVATE (or 0) with
> MAP_SHARED. The kernel is trying to do copy on write for your pages
> (hence the name of function in the error message - do_ write protect
> _page) and that's not going to work with what you are trying to do.
>
> You owe the wizard a pogo stick :-)
>
> Gilad
>
>
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