Date: Mon, 07 Jul 2003 02:48:41 +0200 From: Marcin Dalecki <mdcki@gmx.net> To: dickey@herndon4.his.com Cc: current@freebsd.org Subject: Re: /dev/shm Message-ID: <3F08C369.8080207@gmx.net> In-Reply-To: <20030707001443.GA1530@invisible-island.net> References: <3F08B199.3050409@comcast.net> <3F08B79B.2040805@gmx.net> <20030707001443.GA1530@invisible-island.net>
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Thomas Dickey wrote:
> On Mon, Jul 07, 2003 at 01:58:19AM +0200, Marcin Dalecki wrote:
>
>>Myron J. Mayfield wrote:
>>
>>>I attempted to install the linux java sapgui on FreeBSD 5.0, but the jar
>>>file only unpacked part of it. I then copied the files from my Redhat 9
>>>machine. I linked up all the linux libraries needed and attempted to
>>>start it. It gives me an error saying cant find /dev/shm. I tried
>>>adding this to /dev but was unable to. Does anyone have any
>>>information? Thank you. I am somewhat new to FreeBSD but have used
>>>linux for Many years.
>>
>>For some unexcused reason there is the trend in Linux to represent
>>everything as kind of a wired half finished pseudo file system. /proc pipe
>>devicefs sysctl and so on... The list is really long. Even shared memmory is
>>mapped to ehrm.... a filesystem. This is "expected" to be mounted at
>>/dev/shm by the system. You can't expect FreeBSD to follow this path...
>
>
> Linux isn't the only system that does this (learn a little, criticize less).
There is a great span between everything and some things where it makes sense.
Just please compare the devfs *implementations* between FreeBSD and Linux
to see the difference.
Some examples:
/etc/rc.d/init.d# cat /proc/meminfo
total: used: free: shared: buffers: cached:
Mem: 526184448 515764224 10420224 0 43528192 353251328
Swap: 536862720 0 536862720
MemTotal: 513852 kB
MemFree: 10176 kB
MemShared: 0 kB
Buffers: 42508 kB
Cached: 344972 kB
SwapCached: 0 kB
Active: 332328 kB
ActiveAnon: 79088 kB
ActiveCache: 253240 kB
Inact_dirty: 8932 kB
Inact_laundry: 0 kB
Inact_clean: 125308 kB
Inact_target: 93312 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 513852 kB
LowFree: 10176 kB
SwapTotal: 524280 kB
SwapFree: 524280 kB
/etc/rc.d/init.d#
Wonderfull well tought out conscise and dense design isn't it?
Or maybe:
/etc/rc.d/init.d# cat /proc/filesystems
nodev rootfs
nodev bdev
nodev proc
nodev sockfs
nodev tmpfs
nodev shm
nodev pipefs
ext2
nodev ramfs
iso9660
nodev devpts
ext3
nodev usbdevfs
nodev usbfs
nodev binfmt_misc
/etc/rc.d/init.d#
And this is 2.4 kernel not the "upcomming" 2.6
Oh and I know well about the motivation behing /dev/shm - the excuse is called
"POSIX shm semantics". Which are broken in first place and never got over the
"standard" draft state.
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