[kde-linux] Very ugly image in X root window.

[James Tyrer]

On 11/13/2011 12:45 AM, Duncan wrote:
> James Tyrer posted on Sat, 12 Nov 2011 19:24:48 -0700 as excerpted:
>
>> But, I probably won't have to worry about it any more since I just
>> installed 4 GiB of RAM.  System does run much faster.
> =:^)
>
>> You can't use all of it with 32 bits -- KInfoCenter says it sees
>> 3.22 GiBs.  I haven't decided whether to do 64 bit.  I will have
>> to read up on it.  First question is whether I can have only the OS
>> as 64 bit.
> Only the OS?  Which bit do you consider the OS?  Do you mean only the
> kernel, not userspace?  I've just never heard someone say they want only
> the OS as 64-bit before, and it struck me as definitely odd and funny
> sounding, because on Linux where most of the apps are supplied by the
> distro, there really is no clear dividing line between OS and non-OS.
> The clearest dividing line is kernel/userspace.
Actually, there is a clear dividing line if you don't run ONLY the 
Kernel as 64 bit.  You notice this when you first build the system from 
scratch.  There is a small list of libraries and apps that are necessary 
to run the Kernel.  Do I understand that these would have to be 
installed as both 32 bit and 64 bit since some 32 bit apps might call them?

> Most folks with any knowledge would probably include the libc (normally
> glibc but occasionally a different alternative), a more or less POSIX
> compliant shell (normally bash), the init system (traditionally a sysv
> style init, but now days systemd is popular), probably udev, likely grep/
> sed/head/etc, as often used in the initscripts, etc.  Some would include
> xorg and presumably a default desktop environment, tho others wouldn't.
>
> But... there's really no clear dividing line in all that, only the one
> between kernelspace and userspace, and really no easy place to divide
> between 32-bit and 64-bit, except between userspace and kernelspace, so
> seeing discussion of only the OS being 64-bit appears odd indeed, to
> anyone who has even sideways-glanced at the situation.
>
> Meanwhile, do I recall correctly that you run LFS, and compile everything
> from sources yourself?
>
> If so:
>
> 1) What you said about 32-bit isn't entirely correct.  The 32-bit x86
> Linux kernel has a number of different configuration options in regard to
> memory.
>
> First, there are the so-called "normal" modes, which split 4 GiB of
> address space between the kernel and the apps.  IDR which is considered
> normal-normal since I've been on 64-bit amd64 (x86_64) since I had enough
> memory to matter, but the split can be 2:2, 1:3 or 3:1 user/kernel.
> These modes do indeed allow access to only ~3-3.5 gigs, due to the 32-bit
> PCI-hardware I/O region at the top of the 4-gig memory address space.
> Note that this hardware I/O region is taken from the address space
> assigned to the kernel, so if split it 3 gig user, 1 gig kernel, that
> forces the operating kernel into, in your case, about a quarter-gig of
> address space, which isn't a lot for address randomization, etc.  That's
> rather tight.
And so, you have answered the question.  I would want to run only the 
Kernel as 64 bit so that it could address a full 1 GB of memory and 
leave 3 GB for the applications.  That is the main advantage of 64 bit 
-- the ability to address more memory.

<Duncan's ramblings edited out to save bandwidth>

  --

-- 
James Tyrer

Linux (mostly) From Scratch