Re: [patch] printk from userspace

From: Benjamin LaHaise (bcrl@redhat.com)
Date: Tue Aug 13 2002 - 23:35:05 EST


On Tue, Aug 13, 2002 at 09:26:45PM -0700, Linus Torvalds wrote:
> That said, I like the notion. I've always hated the fact that all the
> boot-time messages get lost, simply because syslogd hadn't started, and
> as a result things like fsck ran without any sign afterwards. The kernel
> log approach saves it all in one place.
>
> But /dev/console just sounds potentially _too_ noisy.

/dev/kmsg was another suggestion for the name. But please revert the
yet-another-syscall variant -- having a duplicate way for logging that
doesn't work with stdio just seems sick to me (sys_syslog should die).
Something like the following untested code is much better.

                -ben

-- 
"You will be reincarnated as a toad; and you will be much happier."

diff -urN v2.5.31/drivers/char/mem.c foo/drivers/char/mem.c --- v2.5.31/drivers/char/mem.c Fri Aug 2 11:41:29 2002 +++ foo/drivers/char/mem.c Wed Aug 14 00:34:33 2002 @@ -579,6 +579,24 @@ write: write_full, }; +static ssize_t kmsg_write(struct file * file, const char * buf, + size_t count, loff_t *ppos) +{ + char tmp[1025]; + + if (count > 1024) + count = 1024; + if (copy_from_user(tmp, buf, count)) + return -EFAULT; + tmp[count] = 0; + printk("%s", tmp); + return count; +} + +static struct file_operations kmsg_fops = { + write: kmsg_write, +}; + static int memory_open(struct inode * inode, struct file * filp) { switch (minor(inode->i_rdev)) { @@ -608,6 +626,9 @@ case 9: filp->f_op = &urandom_fops; break; + case 11: + filp->f_op = &kmsg_fops; + break; default: return -ENXIO; } @@ -634,7 +655,8 @@ {5, "zero", S_IRUGO | S_IWUGO, &zero_fops}, {7, "full", S_IRUGO | S_IWUGO, &full_fops}, {8, "random", S_IRUGO | S_IWUSR, &random_fops}, - {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops} + {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops}, + {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops}, }; int i; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/



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