On 1/12/24 13:07, Alan Corey wrote:
> Are you forgetting that 64 bit is slower? In the arm world where it's
> easily switchable 64 bit is pokey when you don't need it.
>
Thank Alan, to put numbers behind that, linuxcnc has a thing called
latency-test on an rpi4b the armhf kernel I built from 4.19 srcs, can
respond to an irq in 12 microseconds, this in 2018. in 2023, an arm64
rt-preempt kernel can only do that in around 50 microseconds. The huge
majority of that time is a increased size of the stack frame it has to
put away and then reload the environment to handle the interrupt.
> On Fri, Jan 12, 2024, 12:54 PM <rhys@neoquasar.org
> <mailto:rhys@neoquasar.org>> wrote:
>
>
>
> Sent from my mobile device.
>
> ------------------------------------------------------------------------
> *From:* YunQiang Su <wzssyqa@gmail.com <mailto:wzssyqa@gmail.com>>
> *Sent:* Friday, January 12, 2024 10:11
> *To:* rhys@neoquasar.org <mailto:rhys@neoquasar.org>
> *Cc:* noloader@gmail.com <mailto:noloader@gmail.com>;
> debian-kernel@lists.debian.org
> <mailto:debian-kernel@lists.debian.org>; debian-arm@lists.debian.org
> <mailto:debian-arm@lists.debian.org>; debian-devel@lists.debian.org
> <mailto:debian-devel@lists.debian.org>;
> debian-release@lists.debian.org <mailto:debian-release@lists.debian.org>
> *Subject:* Re: Ability to further support 32bit architectures
>
> <rhys@neoquasar.org <mailto:rhys@neoquasar.org>> 于2024年1月12日周五
> 23:59写道：
> >
> > Keeping in mind that I am new to this arena...
> >
> > I have some Intel systems - both 64-bit and 32-bit - that I might
> be able to use as build platforms.
> >
>
> I guess all of your hardwares are 64bit. You setup different OS on them.
>
> No. I have multiple 32-bit systems, one of which is Intel.
>
> > What does the Debian team need from me to be able to use these
> systems?
> >
>
> It's not about performance of hardware. It is about some limitation
> of 32bit.
> 2 examples for it:
> 1. if we use 32bit value for time, it will overflow in 2038, then
> your time will be shown as 1900.
> https://en.wikipedia.org/wiki/Year_2038_problem
> <https://en.wikipedia.org/wiki/Year_2038_problem>
> 2. A single process (or maybe APP, not precisely), can only use UP
> to 4GiB RAM.
> In fact on most system the value is less than 4GiB:
> on intel32, it is 3GiB
> on mips32, it is 2GiB
> But currently, it is not enough, for example, when we build a
> big APP, it will need much more RAM.
> The RAM does install in your Rack, but you can NOT use it.
> https://en.wikipedia.org/wiki/3_GB_barrier
> <https://en.wikipedia.org/wiki/3_GB_barrier>
>
> > I can't guarantee they'll be FAST, but I'll do what I can to make
> them EFFECTIVE.
> >
>
> If you are really need 32bit system. Maybe you can say out why you
> *REALLY* need it.
> For most users, the suggestion is: upgrade to 64bit.
>
>
> That's not at all what I was asking or talking about.
>
> --J
>
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis