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> In hardware terms, a pSeries and an iSeries are the same, with different microcode customizations loaded into the processors I don’t think the microcode is d

> In hardware terms, a pSeries and an iSeries are the same, with different microcode customizations loaded into the processors I don’t think the microcode is different. It is true there are a few CPU instructions (memory tagging related) which were added for IBM i, but they are documented and there is nothing technically stopping some other OS from using them. I thought the difference was that AIX, IBM i and Linux use different firmware. The firmware isn’t CPU microcode, it is just ordinary (albeit privileged) POWER machine code. Or to be more accurate, the POWER firmware has this concept of loadable modules (LIDs), and IBM i needs certain special firmware modules loaded which aren’t required for any other OS. This is why, even though QEMU can run Linux for POWER fine, and even AIX, it can’t boot IBM i-no one outside of IBM really knows what those special firmware modules do or their API, but without them the OS can’t boot. It is unlikely to ever happen without some serious reverse engineering, which would likely upset IBM and cause them to unleash their army of lawyers

rbanffy 4y ago
> no one outside of IBM really knows what those special firmware modules do or their API This is a thing that always gets me thinking. How is it possible that the firmware has never been dumped? It's not like there wouldn't be some market for a machine that could emulate an IBM i in jurisdictions where requiring IBM hardware to run the OS is illegal.
- skissane 4y ago
  > It's not like there wouldn't be some market for a machine that could emulate an IBM i in jurisdictions where requiring IBM hardware to run the OS is illegal. From a business perspective, in most major markets, too much risk of being sued by IBM. There are some countries in which you don’t have to worry about that - but those countries have few or no IBM i systems, so are likely too small a market to make it worthwhile I’m sure some hobbyist somewhere will build an IBM i emulator eventually - IBM probably wouldn’t bother suing a hobby project, even if the law was on their side. But it is a pretty niche thing, so the intersection of sufficient skills and sufficient interest is likely to be quite small - that eventually may take a long time. I myself think about it sometimes, but I doubt I’d ever do it - don’t have the time, other things I’d rather work on, don’t have any actual IBM i hardware and I think you’d really need that for reverse engineering

rbanffy 4y ago

> no one outside of IBM really knows what those special firmware modules do or their API This is a thing that always gets me thinking. How is it possible that the firmware has never been dumped? It's not like there wouldn't be some market for a machine that could emulate an IBM i in jurisdictions where requiring IBM hardware to run the OS is illegal.

skissane 4y ago
> It's not like there wouldn't be some market for a machine that could emulate an IBM i in jurisdictions where requiring IBM hardware to run the OS is illegal. From a business perspective, in most major markets, too much risk of being sued by IBM. There are some countries in which you don’t have to worry about that - but those countries have few or no IBM i systems, so are likely too small a market to make it worthwhile I’m sure some hobbyist somewhere will build an IBM i emulator eventually - IBM probably wouldn’t bother suing a hobby project, even if the law was on their side. But it is a pretty niche thing, so the intersection of sufficient skills and sufficient interest is likely to be quite small - that eventually may take a long time. I myself think about it sometimes, but I doubt I’d ever do it - don’t have the time, other things I’d rather work on, don’t have any actual IBM i hardware and I think you’d really need that for reverse engineering