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safety-critical systems can use ROMsafety-critical systems can use ROMPosted Oct 18, 2006 22:53 UTC (Wed) by man_ls (subscriber, #15091)In reply to: safety-critical systems can use ROM by bronson Parent article: FSF should separate GPLv3 changes (Linux.com) Putting a small portion of software in ROM and letting the rest be user-serviceable helps freedom. Having a device which can be upgraded by the manufacturer but not by you does not help freedom; the software might as well be burnt in ROM and we would not have the illusion of freedom. Sometimes small locks and visible bars help freedom.
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No one uses ROM anymore, get over it already Posted Oct 19, 2006 1:59 UTC (Thu) by svkelley (guest, #37299) [Link] What people don't seem to understand is that no one uses ROM any more in embedded devices. It is all programmable flash. What is clear is that the people working on the GPLv3 draft really lack any knowledge of modern embedded systems and the components that make them up.
Sean
Not all flash is updateable Posted Oct 19, 2006 7:23 UTC (Thu) by man_ls (subscriber, #15091) [Link] I would imagine that not all flash memory inside a device must be made user-serviceable. Even that it takes some effort to make it updateable from software. So, set the flash contents in the factory and just avoid upgrades on the field, and effectively you have a ROM, right?
Not all flash is updateable Posted Nov 2, 2006 17:27 UTC (Thu) by wookey (subscriber, #5501) [Link] Not really. Both nor and nand flash are intrinsically read/write. You could wire up a flash chip with the write line tied down so it couldn't be used bu then there is a problem about how to get the code into the device in the first place. Myabe you could do it with JTAG, but normally you have use JTAG on the CPU which then used the write line to get data into the chip.
In theory you could put some content in the chip before soldering it down, but the whole production process is now set up assuming that you don't have to do this sort of thing any more (and we all save money because of it).
So the 'just put it in ROM' is not a trivial thing. It requires significant design and production changes, if it is possible at all.
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