Hi Erik,
Thanks. I got it.
I am writing simple module and testing them.
I am trying to write a MACRO to define my own LOGLEVEL for the printk statement
See it below:
#define PDEBUG (Level, fmt, args...) do { if (Level == 0)
printk("MYDRV:"fmt,
##args) else if (Level ==1)
printk("MYDRV:<%s> "
fmt, __FUNCTION__, ##args) } while0
Can you suggest some more extra detailed log levels that I can add ti
this MACRO?
- Mukund
On 3/26/08, Erik Mouw <mouw@xxxxxxxxxxxx> wrote:
> On Wed, Mar 26, 2008 at 02:33:58PM -0700, bhanu nani wrote:
> > I have completed reading the LLD3 and The Design of Unix Operating Sysem.
> > I have just started writing my own version of LLD example drivers.
> > My machine runs on FC8.
> >
> > Theoritically, understand that the buffercache only avialable for
> > Block driver not char devices. I wrote a scull type char driver.
> >
> > I do this from the APP:
> > fwrite(buf, 1, 2, fd)
> > rewind()
> > fread(buf, 1, 1, fd)
> > fwrite(buf, 1, 1, fd)
> >
> > During the fread operation, driver gets a read of 4096 bytes from the
> > application whereas the application is trying ot read only 1 byte.
> > This looks like file system buffer cache.???
>
> No, what you see is libc buffering. Just strace your program and you
> will see it issueing a 4096 byte read() system call. Also note that
> read() takes a file descriptor and not a pointer to a FILE structure.
>
> If you really want to read/write a single byte, use read()/write()
> instead of fread()/fwrite() (and lseek() instead of rewind()).
>
>
> Erik
>
> --
> Erik Mouw -- mouw@xxxxxxxxxxxx
>
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