PTYs

Ken Moffat ken at kenmoffat.uklinux.net
Wed Feb 18 15:10:30 PST 2004


On Wed, 18 Feb 2004, Albert Reiner wrote:

>
> (I don't know what the blk: and cs: lines mean, whether they are
> connected to the final vesafb note, and what exactly the significance
> of that one is.)

 Me neither, I've never found much use for VESA fb.
>
> (but they *are* unreadable...)
>

 I believe you, it depends in a small part on font selection (which may
come down to what your graphics card defaults to), and in large part how
big your monitor is, and how close you sit.

> >  Or maybe just build the kernel without framebuffers if you only want
> > 80x25.
>
> If I do so, will I still be able to use X on those rare occasions when
> I need to?
>

 Yes (mostly).  I believe it's more a problem the other way round
(particularly with early 2.6 kernels), that X stomps all over the
console framebuffer.  The only things that _need_ framebuffers are macs
an suchlike.

> >  Framebuffers definitely seem to slow things down a bit, but on most
> > hardware they'll still comfortably outpace what you can read.
>
> Well, even the 288 lines of dmesg output take around 6.5 seconds to
> scroll by - not that I can read that fast, but I am used to seeing the
> end of so short a file immediately.  Searching in less is extremely
> painful, and I have also noticed that switching to a different console
> greatly speeds up compilations etc when the make output goes to the
> console.
>
> >                                                                What cpu,
> > memory, which framebuffer ?  The "lowest common denominator" (VESA, I
> > think) seems to be particularly slow.
>
> This is an Acer Aspire 1703SM_2.6 notebook:
>
> - CPU: Intel(R) Pentium(R) 4 CPU 2.60GHz
>
> - MemTotal: 513356 kB
>
> - /proc/fb: 0 VESA VGA
>

 Wow, that _is_ slow for such a beast.

> So it seems I am running the least common denominator on my host, and
> I can live with that for the moment.
>
> However, where in the book do I have to make sure I don't end up with
> the same problem on the new LFS?  I gather it is the "make menuconfig"
> step in Chapter 8, "Installing Linux-...".
>

 The selection is under Console drivers, but you have to enable "prompt
for development..." in Code maturity level options.

> So, if Vesa is particularly slow, what about other framebuffers?  How
> can I find out which one will work with my hardware (there is a
> sticker mentioning "nVIDIA GeForce FX Go5600, 64MB" on the notebook)?
> I see that Knoppix has a great many of them as modules - can I just
> modprobe something and see what happens, or might that have adverse
> effects?
>

 Yes, and yes. (nothing like hedging your bets, is there ?)  I really
don't know.

 Dunno, I don't but nVidia these days.  Maybe the riva ?  But if you
really need 80x25 to see it comfortably, it probably won't help much.

> Also, what about Chapter 6, "Installing LFS-Bootscripts-...": does the
> switching to Vesa VGA framebuffer occur before or after the
> /etc/init.d/ scripts are run?
>

 I would guess it's before.

Ken
-- 
Brighton tops UK Jedi league
http://www.theregister.co.uk/content/28/35186.html




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