* Michael Banck <mbanck@gmx.net> [030110 06:26]: > Hi, > > I've talked to AMDs Open Source Relation Engineer, Marc Miller about a > possible Debian x86-64 port, see his (quite positive, IMHO) answer > below. AFAIK, single developers accepted NDAs for porting purposes in > the past, am I mistaken? I'd hope such an NDA would be time limited, > e.g. until the Opteron is officially available. Another issue would be > hosting a possible hardware loan, I've heard on irc that Brainfood might > be able to do it in a way acceptable to AMD. Great work. Thanks, Michael. > I am definetly lacking the knowledge, experience and time to do a port, > but I guess/hope there are couple of us who would be interested in > working on a x86-64 port, even under an NDA? Marco d'Itri already said > he would generally be interested. It might be wise to form a porting > team and strategy before everybody bombs Marc with individual requests. I am definately interested in joining this team! > I'd suspect that AMD would be more willing to share/give away hardware > if they knew that we were strongly committed to a port. Anyway, we could > use the time being without access to hardware to discuss matters about > the port, e.g. if a mixed x86/x86-64 userspace is feasable or even > possible or if we could cross-compile some important toolchain stuff > in the meantime. I will assume that if we do any work we must start with a 64-bit kernel. From what I understand, the hardware provides a "64-bit long mode" in which the kernel could run and allow for 32-bit applications to execute without recompilation (this later mode is referred to as compatibility submode of long mode). However, recalling Andi Kleen's talk at OLS two years ago, I believe that a recompile will still be needed for these 32-bit apps due to an ABI change on the x86-64 platform. I am pretty sure all the changes in user-space would be localized to glibc -- as it implements the ABI's API to the rest of user application. That is not too bad. However, since we are already recompiling applications on the x86-64 to run in 32-bit more, we should recompile them in 64-bit mode to improve performance (wider registers, 8 additional general purpose registers, etc). There may be some apps that will (initially) not work in 64-bit mode, and for these we use 32-bit mode. The only snag with this is that we now need two glibc's on the system: the 32-bit one and the 64-bit one. B. -- WebSig: http://www.jukie.net/~bart/sig/
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