On 02/05/2012 02:41 AM, Aurelien Jarno wrote:
On Thu, Feb 02, 2012 at 03:38:27PM -0800, David Daney wrote:On 02/02/2012 02:42 PM, Aurelien Jarno wrote:On Wed, Feb 01, 2012 at 03:56:33PM -0800, David Daney wrote:Hi,Hi,We (Cavium, Inc.) are interested in working with one or more people to create a MIPS 64 port of Debian. As part of the effort, we can make available one or more fairly high end machines. These would be cn5650 (12 CPU SMP) based, or similar, with 4GB of RAM and a large SATA disk. See: http://cavium.com/OCTEON-Plus_CN56XX.html These are running unmodified Linux 3.2 kernels with mips/Squeeze installed and at first would be big-endian only. We can also run little-endian in the future, but we are interested in attacking the big-endian problem first.I think Debian would be interested in having a 64-bit MIPS port, but the main problem is to have enough people interested and providing manpower. The current mips and mipsel ports are not in a very good state, and are already lacking manpower to fix the existing issues. That's why this part is important, and it would be difficult to convince the release team and the community in general to add a 3rd mips(el) port if the already existing ones are not well maintained.Although nothing can be guaranteed, I think there might be more interest in fixing problems in a port if the port addressed our needs. If you look at the types of MIPS machines out there where running a full distribution makes sense, there are many 64-bit systems. Old SGI gear off of e-bay, Cavium, Loongson, etc.That's probably a good point, but let me ask you what are exactly your needs? That's probably something very important to define before starting a new port.
The o32 ABI is much slower that n32 for many applications. I won't bother quantifying it, so lets take that as a given. On 64-bit hardware, n32 gives the best performance.
Our needs are for a good performing Linux distribution with the largest set of supported packages possible. Debian fits the bill on the number of supported packages part, but could be better performance wise with n32 support.
If you are interested by speed, you can start a n32 port with loongson3 or MIPS64R2 instruction set, but on the other hand less users will be interested by such a port.
We shouldn't go overboard, so I would propose supporting mips4 (a subset of mips64R2). That would allow us to run on old SGI boxes as well as Cavium/Octeon, Loongson, RMI, etc.
Same, do you want a hard-float port, soft-float?
I would want hard-float. Many CPUs have hardware FPUs and soft-float is a little too kludgy.
The problem there is to find the right compromise between feeling your needs and interesting as many users (and potential contributors) as possible.
Agreed.
Unfortunately new embedded hardware is still using MIPS32 based cores, so a n32 port can't work on it. That's why with limited manpower we prefer to have only a o32 port in Debian.
At this point I would just like to try something experimental, and hope that it could evolve into an official port. I am not so presumptuous to expect it to be an official port until its usefulness is demonstrated.
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So if a new MIPS port is created, I really advise to create a full 64-bit port.I would like that too, but really as something that could be mixed and matched in a single instalation. But it would be more work to do both n64 and n32.Multiarch in Debian will allow a user to mix both n32 and n64, but it still needs the two ports to be created.
The two ABIs (n32 and n64) are so similar that it shouldn't be difficult to do both...
David Daney