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flak7
n00b
Joined: 17 Sep 2005
Posts: 44
Location: Poland
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 Posted: Fri Mar 10, 2006 10:54 pm Post subject: flags and 64bit |
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Hello everyone
I was searching for 64 bit Linux for my U5. I found Debian & Gentoo. Unfortunately Debian is 64 bit kernel and 32 bit user space, so I got Gentoo (stage 3). I am not a "true" Gentoo user - I just need Tux on SPARC. Please tell me will those flags support full 64 bit mode:
CFLAGS="-Os -mcpu=ultrasparc -fomit-frame-pointer -s -pipe"
CHOST="sparc-unknown-linux-gnu"
CXXFLAGS="-Os -mcpu=ultrasparc -fomit-frame-pointer -s -pipe"
I do not want any heavy tweaking. I need only a stable (quite fast  64 bit desktop for may home network.
BTW: I use gcc 3.3.5 + vanilla kernel 2.4.31 if it makes any difference.
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corsair
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Joined: 06 Oct 2003
Posts: 451
Location: Aachen, Germany
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| Posted: Sat Mar 11, 2006 7:48 am Post subject: |
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Gentoo/SPARC64 runs also using a 64 bit kernel and 32 bit userland by default. There *is* a profile which is 64 bit userland by default, but it is not supported in any way and there do *not* exist any stages (as far as I searched on the mirror). The profile name is default-linux/sparc/sparc64-multilib/dev/64bit-default. You could be one of the braves, who try it out, but don't expect any great speedups, unless you are doing some crazy scientific stuff. Actualy 64 bit userland is slower in many cases.
I suggest you to stick with a 64 bit kernel and 32 bit userland. |
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Syntaxis
Guru
Joined: 28 Apr 2002
Posts: 511
Location: London, UK
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| Posted: Sat Mar 11, 2006 9:56 am Post subject: Re: flags and 64bit |
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| flak7 wrote: | | Unfortunately Debian is 64 bit kernel and 32 bit user space |
No, it isn't.
| Debian AMD64 port page wrote: | A complete 64bit userland
The AMD64 port is thoroughly 64bit, allowing the user to benefit from all advantages this architecture has compared to i386:
* no memory segmentation in low and high memory
* up to 512GiB virtual address space per process (instead of 2GiB)
* 1TiB physical memory support instead of 4GiB (or 64GiB with the PAE extension)
* 16 general purpose registers in the CPU instead of 8
* gcc defaults to SSE2 math instead of 387 FPU
* gcc omits frame-pointers by default at -O2
* compilation time optimization uses a common base for AMD64/EM64T instead of legacy i386 cruft
* memory pages are not executable by default
Native execution of legacy 32bit binaries is supported by the kernel, and core libraries are provided by the ia32-libs package. |
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mark_alec
Bodhisattva
Joined: 11 Sep 2004
Posts: 6066
Location: Melbourne, Australia
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| Posted: Sat Mar 11, 2006 10:02 am Post subject: Re: flags and 64bit |
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| Syntaxis wrote: | | flak7 wrote: | | Unfortunately Debian is 64 bit kernel and 32 bit user space |
No, it isn't. |
They are talking about sparc, not amd64. So they are correct about debian for the sparc having a 32 bit user space.
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Syntaxis
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Joined: 28 Apr 2002
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Location: London, UK
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| Posted: Sat Mar 11, 2006 10:28 am Post subject: |
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| mark_alec wrote: | | They are talking about sparc, not amd64. |
Lol, good point.  Durrr....
/me needs sleep
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flak7
n00b
Joined: 17 Sep 2005
Posts: 44
Location: Poland
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| Posted: Sat Mar 11, 2006 1:06 pm Post subject: |
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Can't get it.
Linux supports full 64bit on AMD64 and the system can be even 20% faster.
Linux full 64bit on SPARC(64) and the system gets slower?!
So why Solaris 7< are full 64bit (on SPARC)?
Are there any plans of getting full 64bit SPARC support to Gentoo? Stable and official I mean.
As I understand the flags I stated will get me 32bit user land, but I builded with those flags my vanilla kernel.
How to ensure that the kernel will be 64bit?
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GenTimJS
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Joined: 03 May 2003
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Location: NH, USA
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| Posted: Sat Mar 11, 2006 2:33 pm Post subject: |
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When talking 64bit sparc and 64bit amd64 you need to remember a key point:
They are totally different.
That being said, consider that with amd64 when you run in 64bit mode you gain advantages over running 32bit mode on the same chip ... double memory registers and such ... Nothing simmilar happens on sparc, and due to the nature of memory handling on sparc many applications will consume considerably more system RAM running in naitive 64bit mode than naitive 32bit mode.... for most circumstances, a 32bit userland on a linux sparc system will be faster.
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blu3bird
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Joined: 04 Oct 2003
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Location: Munich, Germany
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| Posted: Sat Mar 11, 2006 4:30 pm Post subject: |
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| flak7 wrote: | | So why Solaris 7< are full 64bit (on SPARC)? |
Solaris 10 does not come with a fully 64bit userland
Most progs, which have no need for 64bit, are 32bit, like /usr/bin/bash
Other progs, like oracle, are indeed 64bit
I don't have Solaris installed so I can't say for sure...if I'm wrong please correct me
| flak7 wrote: | As I understand the flags I stated will get me 32bit user land, but I builded with those flags my vanilla kernel.
How to ensure that the kernel will be 64bit? |
If the kernel boots, it is 64bit. different from amd64 a 32bit kernel will not boot on sparc64
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gust4voz
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Joined: 09 Sep 2003
Posts: 373
Location: Buenos Aires, Argentina
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| Posted: Sat Mar 11, 2006 9:39 pm Post subject: |
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Adding to GenTimJS comment (which is right) when you run 64-bit binaries you get extra padding/alignment - that makes for bigger binaries, which of course occupy more ram and need more ram bandwdith. Memory pointers are also doubled in size. Nice tradeoff huh?
Granted, 64-bit binaries are useful in some cases, like a single big process requiring access to more than 4GB of ram. That's the reason usually databases are the preferred candidates for that.
On SPARC64 you can access the extra registers and opcodes (including VIS) while still running 32-bit binaries, so you really don't get any benefit.
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Gustavo Zacarias
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flak7
n00b
Joined: 17 Sep 2005
Posts: 44
Location: Poland
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| Posted: Sun Mar 12, 2006 12:49 am Post subject: |
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O.K. I get it. Well as Debian Sarge is the last Debian on SPARC and I do not know any other mature/supported distributions on SPARC I will stick to Gentoo. I am a bit disappointed about SPARC, but at lest I have useful 64 bit kernel I think.
BTW: Seems that Sun lies.
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Gentoo on Sparc
