On Thursday 13 October 2005 06:24 am, Mike Dodd wrote:
> > tmpfs is not an alternative to ramdisks. A kernel can support both.
>
> Agreed. But my question was, if tmpfs is used is it still NECESSARY to
> do the stuff with ramdisk? My Google search results seem to indicate
> it is not.
I also think it's not.
> It appears that tmpfs doesn't require (for example) a
> /dev/ram device or creating a filesystem on it. tmpfs appears to be a
> complete filesystem itself, and is ready for mounting.
Yes, and it appears that the tmpfs filesystem is initialized differently
than ramfs is. With ramfs the size of the ramdisk is specified on the
command line before booting Linux, but with tmpfs the size is set _after_
Linux is booted. [In Debian this setting is in /etc/default/tmpfs and the
default is half of system ram.] This seems to be mounted
by /etc/init.d/mountvirtfs, and all of this is part of the 'initscripts'
package.
By default the tmpfs filesystem is mounted in the directory /dev/shm by the
initscripts, even if tmpfs is not listed in /etc/fstab.
[Note: I don't have a TS-7250 as of yet, so all of the above is in
reference to Debian on an x86]
In addition, it seems the tmpfs filesystem grows and shrinks with usage,
whereas a ramdisk is allocated with a fixed amount of physical ram.
> > If the kernel was compiled with tmpfs it is there - period.
> > There is a list of inbuild filesystems that the current kernel supports
> > cat /proc/filesystems
>
> Thank you; I'll check that out.
This shouldn't be an issue now, but apparently on kernels prior to 2.4.6
the output of /proc/filesystems would show tmpfs even if it was not
available. That has since been fixed.
> > I'm at home so I've just checked the config file for my last
> > kernel build (last Xmas! boxing day actually - sad) and it appears
> > the TS build doesn't enable TMPFS. As far as I remember, I only
> > enabled a couple of kernel options ontop of the basic TS build.
> > It appears that RAMFS support is built in.
>
> I'm starting to believe the kernel was built without tmpfs.
That's also what I think is going on.
How difficult is a kernel recompile for a TS-7250, BTW?
- Chris
--
Chris Knadle
------------------------ Yahoo! Groups Sponsor --------------------~-->
Fair play? Video games influencing politics. Click and talk back!
http://us.click.yahoo.com/T8sf5C/tzNLAA/TtwFAA/CFFolB/TM
--------------------------------------------------------------------~->
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/ts-7000/
<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|