Virtio_console usage of early printk

Hi all,

As far as I can see, early_put_chars is not used by virtio_console
because it checks whether there is a port available before using it.
If I understand correctly, this makes it useless because once we have
a port, we can use the regular virtio transport to output things to
the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

Thanks,
François

On (Mon) Mar 22 2010 [18:45:47], François Diakhate wrote:

Hi all,

As far as I can see, early_put_chars is not used by virtio_console
because it checks whether there is a port available before using it.
If I understand correctly, this makes it useless because once we have
a port, we can use the regular virtio transport to output things to
the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

Looks OK to me, Christian, others, could you comment on this please?

Thanks,
François

		Amit

On 22.03.2010, at 18:45, Fran=E7ois Diakhate wrote:

Hi all,
=20
As far as I can see, early_put_chars is not used by virtio_console
because it checks whether there is a port available before using it.
If I understand correctly, this makes it useless because once we have
a port, we can use the regular virtio transport to output things to
the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

On S390 we use the hypercall interface with characters instead of memory =
addresses as parameters. The hypervisor then decides if the character is =
an early printk or a real hypercall.

I'm not sure how PPC handles that - I never used virtio console there.

Either way, early printk does work for S390. So what exactly is this =
patch supposed to fix?


Alex=

Am Dienstag 23 M=E4rz 2010 03:16:20 schrieb Amit Shah:

On (Mon) Mar 22 2010 [18:45:47], Fran=E7ois Diakhate wrote:

quoted

the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

=20
Looks OK to me, Christian, others, could you comment on this please?

Looks good and boot tested with kuli on s390.

Acked-by: Christian Borntraeger <redacted>

quoted

From 3961f380bbe84a1036ddfc823039cbee31b44dcb Mon Sep 17 00:00:00 2001
From: =3D?utf-8?q?Fran=3DC3=3DA7ois=3D20Diakhat=3DC3=3DA9?=3D <fdiakh@g=

mail.com>

quoted

Date: Thu, 18 Mar 2010 14:48:20 +0100
Subject: virtio: console: Fix early_put_chars usage
=20
Currently early_put_chars is not used by virtio_console because it can =

only be used once a port has been found, at which point it's too late becau=
se it is no longer needed. This patch should fix it.

quoted

---
 drivers/char/virtio_console.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
=20

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_consol=

e.c

quoted

index f404ccf..691ba21 100644

--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c

@@ -645,13 +645,13 @@ static int put_chars(u32 vtermno, const char *buf=

, int count)

quoted

 {
 	struct port *port;
=20
+	if (unlikely(early_put_chars))
+		return early_put_chars(vtermno, buf, count);
+
 	port =3D find_port_by_vtermno(vtermno);
 	if (!port)
 		return 0;
=20
-	if (unlikely(early_put_chars))
-		return early_put_chars(vtermno, buf, count);
-
 	return send_buf(port, (void *)buf, count);
 }

On (Mon) Mar 22 2010 [18:45:47], François Diakhate wrote:

Hi all,

As far as I can see, early_put_chars is not used by virtio_console
because it checks whether there is a port available before using it.
If I understand correctly, this makes it useless because once we have
a port, we can use the regular virtio transport to output things to
the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

Thanks,
François

From 3961f380bbe84a1036ddfc823039cbee31b44dcb Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Fran=C3=A7ois=20Diakhat=C3=A9?= <redacted>
Date: Thu, 18 Mar 2010 14:48:20 +0100
Subject: virtio: console: Fix early_put_chars usage

Currently early_put_chars is not used by virtio_console because it can only be used once a port has been found, at which point it's too late because it is no longer needed. This patch should fix it.

You'll have to give a signed-off-by for the patch.

		Amit

On Tue, Mar 23, 2010 at 9:55 AM, Amit Shah [off-list ref] wrote:

On (Mon) Mar 22 2010 [18:45:47], François Diakhate wrote:

quoted

Hi all,

As far as I can see, early_put_chars is not used by virtio_console
because it checks whether there is a port available before using it.
If I understand correctly, this makes it useless because once we have
a port, we can use the regular virtio transport to output things to
the console. Does the attached patch seem valid ? Feedback from s390
and powerpc users who use this functionality would be appreciated.

Thanks,
François

quoted

From 3961f380bbe84a1036ddfc823039cbee31b44dcb Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Fran=C3=A7ois=20Diakhat=C3=A9?= <redacted>
Date: Thu, 18 Mar 2010 14:48:20 +0100
Subject: virtio: console: Fix early_put_chars usage

Currently early_put_chars is not used by virtio_console because it can only be used once a port has been found, at which point it's too late because it is no longer needed. This patch should fix it.

You'll have to give a signed-off-by for the patch.

               Amit

Sorry, I didn't have access to my computer this morning. Here is the
patch with a sign-off, if you still need it.

François