Messages in this thread | | | From | "Etienne Lorrain" <> | Date | Thu, 12 Mar 1998 11:27:08 +0001 | Subject | mmap() versus read() and embedded systems. |
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Just my $0.02,
Even if you have memory mapped flash as a file system in an embedded environment, with romfs, the main problem is the executable loader: it has to modify (resolve address) of the code you are executing, so this code has to be copyed first in RAM. I am not sure that using static library (instead of ELF) solves completely this problem...
> On Wed, 11 Mar 1998, Michael Lausch wrote: > ... > > But the problem is when you are using Linux on embedded systems > > without any swap (disk) at all. The programs are stored in the FLASH > > RAM so the cost of reading a page from the executable is almost zero, > > but using a swap area is impossible (no, we don't have 20 Meg RAM for > > a RAM swap disk) > > Is this paged flash or memory mapped flash? Ideally an embedded system > would use memory-mapped flash with a filesystem like romfs (? - does it do > this?) that would provide it's own mmap that just maps in the page, still > in flash, into the process on nopage. This way your executables take up > practically no ram under normal circumstances. > ... > -ben ----------- etienne.lorrain@ibm.net -- hdc: irq timeout: status=0xd0 { Busy } -- ide1: reset: success ----------> I like Linux !
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