Memory management in embedded linux

If you don't have any swap enabled, then you don't have to worry about pages gone missing. On the other hand, if something tries to allocate more memory than is physically available, malloc will fail and the code will have to deal with that failure gracefully.

In the Linux systems I've developed we generally had MMUs built in to the CPU. We rarely configured any swap space, and sized system RAM much larger than our worst-case memory needs.

In the one box where there was swap enabled, we actually allocated a small ram disk and then swapped to that. Crazy, yes, but we were working around a bug in the Linux 2.2.18 (?) VM routines - that code really really expected to have swap available even if it never used it.

I've never built a mobile phone, and if I did I doubt I'd run Linux on it.

Kelly

I think you still have to worry about demand-paging as executable pages are read from "disk" as page faults occur. Of course, there are ways to get around that by pre-loading and then locking a process in memory.

If you're using a RAM disk, is the kernel smart enough to use read-only (e.g. text segment) pages from the file "in-place"?

There will also be page-faults due to copy-on-write attributes on data and bss pages in newly forked processes.

Same here. The examples I'm thinking of booted from Compact Flash and didn't have swap enabled.

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Grant Edwards                   grante             Yow!  RELATIVES!!
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Did you read the pretty comprehensive responses in the Linux group for exactly the same question?

Next time, please, cross-post instead of multi-posting, and think twice about the proper groups.

For the group: the OP got good answers, but he seems to ignore them.

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Tauno Voipio
tauno voipio (at) iki fi

Tauno Voipio wrote in news:GfdBe.238 $ snipped-for-privacy@read3.inet.fi:

Which "the Linux group" are you refering to?

(I'd like to read the responses too and a quick google search didn't turn up any responses from you)

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comp.os.linux.embedded, headers:

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Tauno Voipio
tauno voipio (at) iki fi

Tauno Voipio wrote in news:4UsBe.138$ snipped-for-privacy@read3.inet.fi:

Thank you very much, Tauno.

Best regards, Niels Kristian Jensen

One more reason not to rely on Google for Usenet. I understand they can't handle cross-posts at all. The articles just disappear from all but one group.

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