embedded linux footprint size
Alan C. Chang
I am new for embeded linux development, so, please, forgive me of my stupid
question.
Here is my question --- They are so many embedded linux companies which
claim that they can make smaller footprint size of linux kernel. However, I
was told before that linux is 32bits virtual-memory OS, so it needs some
extra storage space in addition to memory to do swaping and, usually, it is
a hard disk drive. I just wonder if we can have hard disk installed in a
system, do we still need to care about the footprint size of linux kernel ?
I mean, currently, hard disk is so common and so inexpensive and I do think
it can save very much money if you have a linux kernel with 0.5MB rather
than 1MB ?
Thanks !!!
Alan C. Chang 2000-07-17PM
-----------------------------------
Bryan Hackney
>
> Hi Guys,
>
> I am new for embeded linux development, so, please, forgive me of my stupid
> question.
>
> Here is my question --- They are so many embedded linux companies which
> claim that they can make smaller footprint size of linux kernel. However, I
> was told before that linux is 32bits virtual-memory OS, so it needs some
> extra storage space in addition to memory to do swaping and, usually, it is
I have a soft realtime application where swapping is a performance pig, even
with a wide SCSI system. VM swapping is not required in Linux.
I think the more interesting question is: do you want a delicate mechanical
device in your embedded system? Aggressive kernel size management is usually
from having to fit it into too small of a ROM, but also for conserving RAM.
--
Bryan Hackney / BHC / b...@bhconsult.com
http://www.FreeClassAds.com/
http://bhconsult.com/
http://bhconsult.com/bh/pgp.key
Wolfgang Denk
>I have a soft realtime application where swapping is a performance pig, even
>with a wide SCSI system. VM swapping is not required in Linux.
Most embedded Linux devices I've seen so far were just booting from
Flash memory, without any harddisk etc. No swap space used, none
needed. On a 16 MB system you can even compile a Linux kernel without
swap - so this is ennough for a lot of applications.
>I think the more interesting question is: do you want a delicate mechanical
>device in your embedded system? Aggressive kernel size management is usually
>from having to fit it into too small of a ROM, but also for conserving RAM.
You don't have to do any "aggressive kernel size management".
On PowerPC, the full (not specially optimized) Linux kernel (version
2.2.13) including Flash drivers, ext2 Filesystem, TCP/IP and NFS,
gives a compressed image of less than 375 kB.
In a (compressed) image of just 994 kB you can pack the Linux kernel
with networking, web server, and about 560 kB of web pages.
On a board half the size of a credit card you can get the whole
PowerPC system (CPU, 64 MB RAM, 8 MB Flash, Ethernet, serial ports,
USB, LCD/VGA, CAn-Bus, ...) - that's more than enough for most cases.
Wolfgang
--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Web: www.denx.de
A supercomputer is a machine that runs an endless loop in 2 seconds.
Mike
>On a board half the size of a credit card you can get the whole
>PowerPC system (CPU, 64 MB RAM, 8 MB Flash, Ethernet, serial ports,
>USB, LCD/VGA, CAn-Bus, ...) - that's more than enough for most cases.
Where can I find those miniatyre cards capable to run Linux?
Wolfgang Denk
>>On a board half the size of a credit card you can get the whole
>>PowerPC system (CPU, 64 MB RAM, 8 MB Flash, Ethernet, serial ports,
>>USB, LCD/VGA, CAn-Bus, ...) - that's more than enough for most cases.
>Where can I find those miniatyre cards capable to run Linux?
You can get them from us :-) The manufacturer is TQ Components,
Germany.
If you want to see some images, please see
http://www.denx.de/2BLT/gfx007.html
http://www.denx.de/2BLT/gfx008.html
[Sorry - the presentation is in German.]
Wolfgang
--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Web: www.denx.de
All he had was nothing, but that was something, and now it had been
taken away. - Terry Pratchett, _Sourcery_
Rich Hampton
>
> Hi Guys,
>
> I am new for embeded linux development, so, please, forgive me of my stupid
> question.
>
> Here is my question --- They are so many embedded linux companies which
> claim that they can make smaller footprint size of linux kernel. However, I
> was told before that linux is 32bits virtual-memory OS, so it needs some
> extra storage space in addition to memory to do swaping and, usually, it is
> system, do we still need to care about the footprint size of linux kernel ?
> I mean, currently, hard disk is so common and so inexpensive and I do think
> it can save very much money if you have a linux kernel with 0.5MB rather
> than 1MB ?
>
> Thanks !!!
>
> Alan C. Chang 2000-07-17PM
> -----------------------------------
Many, if not most, embedded applications require flash storage rather
than
rotating media for reliability reasons due to harsh environments. Also,
there's a space consideration. If you want to embedd Linux into a hand-
held device, I don't think you'd want a hard disk hanging from it. I'm
currently involved in embedding Linux myself and find that the M-Systems
DiskOnChip devices are great for embedded Linux, although a bit pricey.
There are a number of alternative flash devices that are very small and
fast. If you have an embedded OS/w app that fits into a 2Mb space, then
you can have your system in the size of a pencil eraser.
Rich Hampton
J-Squared