lkml.org 
[lkml]   [2021]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH v2 1/1] rpmsg: add syslog driver
On Thu 11 Nov 04:36 CST 2021, Christian Gmeiner wrote:

> Hi Bjorn
>
>
> > > Allows the remote firmware to log into syslog.
> > >
> >
> > This allows the remote firmware to print log messages in the kernel log,
> > not the syslog (although your system might inject the kernel log into
> > the syslog as well)
> >
>
> Correct.
>
> > > Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
> > > ---
> > > drivers/rpmsg/Kconfig | 8 +++++
> > > drivers/rpmsg/Makefile | 1 +
> > > drivers/rpmsg/rpmsg_syslog.c | 65 ++++++++++++++++++++++++++++++++++++
> >
> > drivers/rpmsg is for rpmsg bus and transport drivers. Client drivers
> > should live elsewhere.
> >
>
> Ahh .. yes.
>
> > But perhaps, rather than having a driver for this, you could simply use
> > rpmsg_char and a userspace tool; if you want to get the remote processor
> > logs into syslog, instead of the kernel log?
> >
>
> I thought about that too (also regarding the rpmsg tty driver) but that means I
> need to start/supervise a user space tool.
>
> > > 3 files changed, 74 insertions(+)
> > > create mode 100644 drivers/rpmsg/rpmsg_syslog.c
> > >
> > > diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
> > > index 0b4407abdf13..801f9956ec21 100644
> > > --- a/drivers/rpmsg/Kconfig
> > > +++ b/drivers/rpmsg/Kconfig
> > > @@ -73,4 +73,12 @@ config RPMSG_VIRTIO
> > > select RPMSG_NS
> > > select VIRTIO
> > >
> > > +config RPMSG_SYSLOG
> > > + tristate "SYSLOG device interface"
> > > + depends on RPMSG
> > > + help
> > > + Say Y here to export rpmsg endpoints as device files, usually found
> > > + in /dev. They make it possible for user-space programs to send and
> > > + receive rpmsg packets.
> > > +
> > > endmenu
> > > diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
> > > index 8d452656f0ee..75b2ec7133a5 100644
> > > --- a/drivers/rpmsg/Makefile
> > > +++ b/drivers/rpmsg/Makefile
> > > @@ -9,3 +9,4 @@ obj-$(CONFIG_RPMSG_QCOM_GLINK_RPM) += qcom_glink_rpm.o
> > > obj-$(CONFIG_RPMSG_QCOM_GLINK_SMEM) += qcom_glink_smem.o
> > > obj-$(CONFIG_RPMSG_QCOM_SMD) += qcom_smd.o
> > > obj-$(CONFIG_RPMSG_VIRTIO) += virtio_rpmsg_bus.o
> > > +obj-$(CONFIG_RPMSG_SYSLOG) += rpmsg_syslog.o
> > > diff --git a/drivers/rpmsg/rpmsg_syslog.c b/drivers/rpmsg/rpmsg_syslog.c
> > > new file mode 100644
> > > index 000000000000..b3fdae495fd9
> > > --- /dev/null
> > > +++ b/drivers/rpmsg/rpmsg_syslog.c
> > > @@ -0,0 +1,65 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +
> > > +#include <linux/kernel.h>
> > > +#include <linux/module.h>
> > > +#include <linux/rpmsg.h>
> > > +
> > > +static int rpmsg_syslog_cb(struct rpmsg_device *rpdev, void *data, int len,
> > > + void *priv, u32 src)
> > > +{
> > > + const char *buffer = data;
> > > +
> > > + switch (buffer[0]) {
> > > + case 'e':
> > > + dev_err(&rpdev->dev, "%s", buffer + 1);
> > > + break;
> > > + case 'w':
> > > + dev_warn(&rpdev->dev, "%s", buffer + 1);
> > > + break;
> > > + case 'i':
> > > + dev_info(&rpdev->dev, "%s", buffer + 1);
> > > + break;
> > > + default:
> > > + dev_info(&rpdev->dev, "%s", buffer);
> > > + break;
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int rpmsg_syslog_probe(struct rpmsg_device *rpdev)
> > > +{
> > > + struct rpmsg_endpoint *syslog_ept;
> > > + struct rpmsg_channel_info syslog_chinfo = {
> > > + .src = 42,
> > > + .dst = 42,
> > > + .name = "syslog",
> > > + };
> > > +
> > > + /*
> > > + * Create the syslog service endpoint associated to the RPMsg
> > > + * device. The endpoint will be automatically destroyed when the RPMsg
> > > + * device will be deleted.
> > > + */
> > > + syslog_ept = rpmsg_create_ept(rpdev, rpmsg_syslog_cb, NULL, syslog_chinfo);
> >
> > The rpmsg_device_id below should cause the device to probe on the
> > presence of a "syslog" channel announcement, so why are you creating a
> > new endpoint with the same here?
> >
> > Why aren't you just specifying the callback of the driver?
> >
>
> Good question. I think I was happy that I got work working somehow. I
> also want to send out
> a documentation update as it is not up to date with the current API.
>

I'd be happy to take any documentation updates - or perhaps we should
reduce the duplication between the kerneldoc and Documentation/*...

> > > + if (!syslog_ept) {
> > > + dev_err(&rpdev->dev, "failed to create the syslog ept\n");
> > > + return -ENOMEM;
> > > + }
> > > + rpdev->ept = syslog_ept;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static struct rpmsg_device_id rpmsg_driver_syslog_id_table[] = {
> > > + { .name = "syslog" },
> > > + { },
> > > +};
> > > +MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_syslog_id_table);
> > > +
> > > +static struct rpmsg_driver rpmsg_syslog_client = {
> > > + .drv.name = KBUILD_MODNAME,
> > > + .id_table = rpmsg_driver_syslog_id_table,
> > > + .probe = rpmsg_syslog_probe,
> > > +};
> > > +module_rpmsg_driver(rpmsg_syslog_client);
> >
> > I would expect that building this as a module gives you complaints about
> > lacking MODULE_LICENSE().
> >
>
> Yeah .. I never built it as a module.
>
> The biggest question I have: do you see any possibility to get such a
> redirection
> driver into mainline? At the moment I have not heard a big no.
>

My feeling is "do we really need a dedicated driver for it", but I do
recognize that it solves a problem for you.

The only "objection" I have is that I personally wouldn't want all the
firmware logs mixed up with the kernel logs. Somehow getting this into
journald separately seems more useful.

Regards,
Bjorn

> --
> greets
> --
> Christian Gmeiner, MSc
>
> https://christian-gmeiner.info/privacypolicy

\
 
 \ /
  Last update: 2021-11-17 16:08    [W:0.119 / U:0.524 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site