Jon Smirl wrote:
> On 6/1/06, Antonino A. Daplas <[email protected]> wrote:
>> Jon Smirl wrote:
>> > On 6/1/06, Antonino A. Daplas <[email protected]> wrote:
>> >> Jon Smirl wrote:
>> >> > On 6/1/06, D. Hazelton <[email protected]> wrote:
>> >> >
>> >>
>> >> Console writes are done with the console semaphore held. printk
>> will also
>> >> just write to the log buffer and defer the actual console printing
>> >> for later, by the next or current process that will grab the
>> semaphore.
>> >
>> > That was my original position too. But Alan Cox has drilled it into me
>> > that this is not acceptable for printks in interrupt context, they
>> > need to print there and not be deferred.
>> >
>>
>> Just to clarify, it's not my position, that's how the current printk code
>> works.
>
> I haven't looked at the code, but if there is just normal console
> running and nothing like X is around, doesn't the console system
> always have the semaphore? If it always has the semaphore then
> interupt context printk's aren't blocked.
>
> I think that interrupt context printk's work today, I have definitely
> seen one printk get inserted into the middle of another on my console.
> How else could you achieve that?
>
foreground calls acquire_console_sem()
foreground process does a printk, printk writes to log buffer
interrupt-> does a printk -> message inserted to log buffer
foreground process calls release_console_sem
release_console_sem() dumps log buffer contents to console driver
Tony
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
