generate a single How to generate a single interrupt on a floppy device

From: John Que
Date: Thu Jul 28 2005 - 07:50:25 EST


I want ,for tracing and debugging purposes, to be able to generate a single
interrupt on a device which (unlike the timer or ide devices, for example) does
not get interrupts very frequently.

Looking at the output of /proc/interrupts (and look at IRQ 6 of the
floppy) shows
that the floppy device interrupt counter is not incremented during time if you
are not constatntly working with it.

So a good candidate for generating a single interrupt can be a floppy.

Is there a way to generate a single interrupt on a floppy device?

I had tried the following:

I mount the floppy;
I see that during the time, sometimes after running ls on a floppy
2 interrupts are generated; and sometimes after ls on a floppy
no interrupts are generated. The same is with
creating a file/reading a file: sometimes there
are interrupts and sometimes there are no interrupts.

So I wrote the following little program:

#define BUFFER_SIZE 2048

char buffer[BUFFER_SIZE] __attribute__((aligned(4096)));

int main()

int fd;
int bytes_read;
int i;
fd = open("/dev/fd0",O_DIRECT);

void* data;

if (fd < 0 )
printf("could not open device\n");


printf("device opened\n");

bytes_read = read(fd,buffer,512);

printf("bytes_read = %d\n",bytes_read);


Each time I ran it I got course :
device opened
bytes_read = 512

But running this program again and again ***DOES NOT*** increase the
number of interrupt on the floppy device IRQ (6).

Any ideas?

Which user space code I should write / Which operation should I do so that each
time I will do it,(again and again) it will generate an interrupt on the
floppy IRQ (6) ?

(BTW I build this program by gcc -D_GNU_SOURCE floppy.c)

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