From: NeilBrown <neilb@suse.de>
To: Tim Bird <tim.bird@am.sony.com>
Cc: Greg KH <gregkh@suse.de>,
linux-embedded <linux-embedded@vger.kernel.org>,
linux kernel <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>, john stultz <johnstul@us.ibm.com>,
Brian Swetland <swetland@google.com>,
Kay Sievers <kay.sievers@vrfy.org>,
Lennart Poettering <lennart@poettering.net>
Subject: Re: RFC: android logger feedback request
Date: Thu, 22 Dec 2011 12:20:26 +1100 [thread overview]
Message-ID: <20111222122026.3a0fae36@notabene.brown> (raw)
In-Reply-To: <4EF27B85.9080801@am.sony.com>
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On Wed, 21 Dec 2011 16:36:21 -0800 Tim Bird <tim.bird@am.sony.com> wrote:
> On 12/21/2011 03:19 PM, Greg KH wrote:
> > That all describes the current code, but you haven't described what's
> > wrong with the existing syslog interface that requires this new driver
> > to be written. And why can't the existing interface be fixed to address
> > these (potential) shortcomings?
>
>
> >> One specific question I have is where is the most appropriate
> >> place for this code to live, in the kernel source tree?
> >> Other embedded systems might want to use this system (it
> >> is simpler than syslog, and superior in some ways), so I don't
> >> think it should remain in an android-specific directory.
> >
> > What way is it superior?
>
> Here are some ways that this code is superior to syslog:
It is certainly nice and simple. It really looks more like a filesystem than
a char device though... though they aren't really files so much as lossy
pipes. I don't think that's a problem though, lots of things in filesystems
don't behave exactly like files.
If you created a 'logbuf' filesystem that used libfs to provide a single
directory in which privileged processes could create files then you wouldn't
need the kernel to "know" the allowed logs: radio, events, main, system.
The size could be set by ftruncate() (by privileged used again) rather than
being hardcoded.
You would defined 'read' and 'write' much like you currently do to create a list of
datagrams in a circular buffer and replace the ioctls by more standard
interfaces:
LOGGER_GET_LOG_BUG_SIZE would use 'stat' and the st_blocks field
LOGGER_GET_LOG_LEN would use 'stat' and the st_size field
LOGGER_GET_NEXT_ENTRY_LEN could use the FIONREAD ioctl
LOGGER_FLUSH_LOG could use ftruncate
The result would be much the same amount of code, but an interface which has
fewer details hard-coded and is generally more versatile and accessible.
NeilBrown
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next prev parent reply other threads:[~2011-12-22 1:20 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-21 22:59 RFC: android logger feedback request Tim Bird
2011-12-21 23:19 ` Greg KH
2011-12-22 0:18 ` john stultz
2011-12-22 0:27 ` Greg KH
2011-12-22 0:47 ` john stultz
2011-12-22 1:09 ` john stultz
2011-12-22 0:42 ` Tim Bird
2011-12-22 0:49 ` john stultz
2011-12-22 1:00 ` john stultz
2011-12-22 0:36 ` Tim Bird
2011-12-22 0:51 ` Greg KH
2011-12-22 1:32 ` Tim Bird
2011-12-22 1:47 ` Greg KH
2011-12-22 2:12 ` Tim Bird
2011-12-22 3:44 ` Kay Sievers
2011-12-22 3:45 ` Greg KH
2011-12-22 3:47 ` Greg KH
2011-12-22 4:12 ` Kay Sievers
2011-12-22 4:22 ` Brian Swetland
2011-12-22 4:43 ` Kay Sievers
2011-12-22 4:47 ` david
2011-12-22 4:58 ` Brian Swetland
2011-12-22 5:07 ` david
2011-12-22 5:21 ` david
2011-12-22 13:40 ` Lennart Poettering
2011-12-22 4:49 ` david
2011-12-22 2:34 ` Kay Sievers
2011-12-22 1:20 ` NeilBrown [this message]
2011-12-22 1:49 ` Greg KH
2011-12-22 2:14 ` Tim Bird
2011-12-22 2:34 ` Brian Swetland
2011-12-22 3:49 ` Greg KH
2011-12-22 4:36 ` Kay Sievers
2011-12-22 5:01 ` david
2011-12-22 4:52 ` david
2011-12-22 5:06 ` Brian Swetland
2011-12-22 5:14 ` david
2011-12-22 5:25 ` Brian Swetland
2011-12-22 6:09 ` Greg KH
2011-12-23 15:22 ` Alan Cox
2011-12-23 16:29 ` Greg KH
2011-12-22 7:05 ` NeilBrown
2012-01-06 20:56 ` Tim Bird
2012-01-06 21:20 ` Greg KH
2012-01-06 22:41 ` Tim Bird
2012-01-06 23:17 ` Greg KH
2012-01-06 23:35 ` Greg KH
2011-12-22 14:59 ` Arnd Bergmann
2011-12-22 15:13 ` Kay Sievers
2011-12-22 4:42 ` david
2011-12-22 0:59 ` David Brown
2011-12-29 0:39 ` Andrew Morton
2012-01-04 15:34 ` Geunsik Lim
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