On 7/26/06, Christian Boon <c.boon@xxxxxxxxxxxxxxxxxxxx> wrote:
Hello,
i've got a question about a page fault:
If have a kernel module that puts data in an array from an external fifo
after an interrupt:
static void *datapointer;
__u16 Data[325];
for (Counter = 0 ; Counter < 325; Counter++)
{
Data[Counter] = readw(datapointer);
}
wake_up_interruptible(&waitqueue);
My application is sleeping on the waitqueue.
in the application:
typedef unsigned char u8;
u8 VideoData[650];
bytes = read(fd, VideoData, sizeof(u8));
So i want to store the array u16 and read in userspace u8.
is this a problem? maybe alignment?
sometimes i get this error:
PraxisSC: unhandled page fault at pc=0x40026df0, lr=0x40089790 (bad
address=0x40026df0, code 0)
pc : [<40026df0>] lr : [<40089790>] Not tainted
sp : bf3fbb58 ip : bf3ffcac fp : bf3ffca8
r10: 0201d6d6 r9 : 00000001 r8 : 0201d6cc
r7 : 0201d6cc r6 : bf3ffd04 r5 : 0201e2bc r4 : 00000001
r3 : 00989680 r2 : 00000000 r1 : 00000000 r0 : 0000000b
Flags: nzcv IRQs on FIQs on Mode USER_32 Segment user
Control: 397F Table: A04DC000 DAC: 00000015
Does this mean that the error occured in my application or is it an
error in my kernel module?
And what is happening here? because it happens after some time, not
immidiately.
One thing is for sure that the page fault is occuring in kernel mode,
so the error is somewhere in your kernel code. As you have not posted
the whole of the code it wont be possible to pin point exactly the
source of this page fault.
Moreover I and wondering how you have used "read()" routine in kernel module ??
Gaurav
thanks in advance,
Chris.
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Gaurav
Email: gauravd.chd@xxxxxxxxx
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