Re: Unexpected kernel device dependency for 'vga* at pci?'

[Paul Goyette]

Thanks for the explanation.

It would seem to me that the vga console code should be separated from 
the rest of the vga driver.  Then it would be rather easy to include the 
console code whenever vga or radeon or the Intel equivalent is 
configured.


I've also noticed that even though no genfb is included in my config 
file, the generated file genfb.h sets NGENFB = 1, while the vga.h file 
contains NVGA = 0.  Some how, this feels like a hack, in order to avoid 
making a similar split (console vs non-console) in the genfb code.


Any way, thanks for all of the extra eyes looking at this, and all the 
explanations.  At least now I know why I need the vga driver, even if 
I'd prefer to omit it.



On Sun, 10 Jul 2016, Michael van Elst wrote:


k...@munnari.oz.au (Robert Elz) writes:


 | While doing this, I've discovered that a radeondrmkmsfb0-based kernel
 | requires that I retain the
 |  vga* at pci? dev ? func ?
 | line in the configuration, even though no such device is ever attached.


The VGA driver is used very early as a console, this happens before
autoconf and before the driver is really attached. For this you only
need the VGA driver included in the kernel.

The kernel would panic without the vga driver on conventional
hardware, but there is a bug in the code.

If the VGA driver is included, the radeon code will detach and reattach
it as a console. When the VGA driver is not included, nothing like
that happens, and the VGA hardware probably isn't mapped anywhere.

In my (intel, not radeon) driver I detach the VGA console

#if NVGA > 0
   iaa.iaa_console = vga_cndetach() ? true : false;
#else
   iaa.iaa_console = false;
#endif

and then map the hardware and attach a wsdisplay as if no
VGA driver had existed.

--
--
   Michael van Elst
Internet: mlel...@serpens.de
   "A potential Snark may lurk in every tree."

!DSPAM:578273e731621319712218!




+--+--++
| Paul Goyette | PGP Key fingerprint: | E-mail addresses:  |
| (Retired)| FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+--+--++

Re: Unexpected kernel device dependency for 'vga* at pci?'

[Michael van Elst]

k...@munnari.oz.au (Robert Elz) writes:

>And as I (kind of said) I never actually tried a config with the "vga* at pci?"
>config included but the wsdisplay* at vga? console ?" omitted, it was both
>or neither for me (just the way it worked out.)

Initially VGA gets attached as console. This has nothing to do
with the config file. It's in the MD consinit() code. This also
attaches an initial wsdisplay screen.

Later VGA may attach at PCI. This provides the regular attachment
and takes over the initial console screen.

Later VGA may attach at ISA. This fails if there is already a
PCI attachment because the hardware is already mapped and cannot
be mapped again.

If there is a radeon driver, it will take priority over the PCI
attachment.  No VGA attaches here but VGA is still the console.
Then it gets a bit kludgy
-- 
-- 
Michael van Elst
Internet: mlel...@serpens.de
"A potential Snark may lurk in every tree."

Re: Unexpected kernel device dependency for 'vga* at pci?'

[Michael van Elst]

k...@munnari.oz.au (Robert Elz) writes:

>  | While doing this, I've discovered that a radeondrmkmsfb0-based kernel 
>  | requires that I retain the
>  |vga* at pci? dev ? func ?
>  | line in the configuration, even though no such device is ever attached.

The VGA driver is used very early as a console, this happens before
autoconf and before the driver is really attached. For this you only
need the VGA driver included in the kernel.

The kernel would panic without the vga driver on conventional
hardware, but there is a bug in the code.

If the VGA driver is included, the radeon code will detach and reattach
it as a console. When the VGA driver is not included, nothing like
that happens, and the VGA hardware probably isn't mapped anywhere.

In my (intel, not radeon) driver I detach the VGA console

#if NVGA > 0
iaa.iaa_console = vga_cndetach() ? true : false;
#else
iaa.iaa_console = false;
#endif

and then map the hardware and attach a wsdisplay as if no
VGA driver had existed.

-- 
-- 
Michael van Elst
Internet: mlel...@serpens.de
"A potential Snark may lurk in every tree."

Re: Unexpected kernel device dependency for 'vga* at pci?'

[Robert Elz]

Date:Sun, 10 Jul 2016 08:32:24 +0800 (PHT)
From:Paul Goyette 
Message-ID:  

  | "Common" yes, but they should not be normal.  The whole point of the 
  | config(1) mess is to be able to properly specify dependencies.

Well, really, the point was to make it easier to build the config files,
that before config(1 or 8) appeared used to be built by hand.  Adding forms
of dependency handling has been a more recent add on - and config files
have (since I first saw one I think) never been "anything goes" - there have
always been "of course if you config X you also need Y" type stuff (apart
from the obvious ones that config itself complains about if you mess up, like
a device at pci, and no pci at anything).

  | As I indicated in a follow-up Email, I still need to include a
  | 
  | vga* at pci? dev ? func ?
  | 
  | to avoid a compiler error.  But I have already removed the
  | 
  | wsdisplay* at vga? console ?
  | 
  | line.  The only wsdisplay line I currently have is
  | 
  | wsdisplay* at radeondrmkmsfb0

That's interesting, I don't have that (or anything like it) in my config
at all - not even commented out.

What I have is (aside from the "at vga?" line) is ...

wsdisplay*  at wsemuldisplaydev?

That one seems to be enough for the kernel to config ...

wsdisplay0 at intelfb0 kbdmux 1: console (default, vt100 emulation)

The other related config that I have are ...

i915drmkms* at pci? dev ? function ?
intelfb*at intelfbbus?

  | which, according to the dmesg, is where it actually gets attached!

which is what gets attached in my case.   I assume one of the files files
has something that makes an intelfb attach a wsemuldisplaydev, or that the
latter is some kind of macro device for the various fb devices.
But I am just guessing...

And as I (kind of said) I never actually tried a config with the "vga* at pci?"
config included but the wsdisplay* at vga? console ?" omitted, it was both
or neither for me (just the way it worked out.)

kre

Re: Unexpected kernel device dependency for 'vga* at pci?'

[Paul Goyette]

On Sun, 10 Jul 2016, Robert Elz wrote:


   Date:Sun, 10 Jul 2016 07:00:11 +0800 (PHT)
   From:Paul Goyette 
   Message-ID:  

 | While doing this, I've discovered that a radeondrmkmsfb0-based kernel
 | requires that I retain the
 |
 |  vga* at pci? dev ? func ?
 |
 | line in the configuration, even though no such device is ever attached.

I saw the exact same problem a month or so ago, but with a system using
integrated intel graphics (core i3 processor).

I didn't bother to mention it as config file inter-dependencies and weirdness
are just "normal" ...


"Common" yes, but they should not be normal.  The whole point of the 
config(1) mess is to be able to properly specify dependencies.



I think I concluded/assumed that the issue may have really related to the

wsdisplay*  at vga? console ?

line that also had to be deleted (there being no vga? at anything left
in the config - or in the console messages on a GENERIC boot) leaving
nothing marked as "console" - whether that's actually true or not I didn't
bother to find out - I put that entry back, and so had to also return the
vga? at .. config, and after that, it all worked.


As I indicated in a follow-up Email, I still need to include a

vga* at pci? dev ? func ?

to avoid a compiler error.  But I have already removed the

wsdisplay* at vga? console ?

line.  The only wsdisplay line I currently have is

wsdisplay* at radeondrmkmsfb0

which, according to the dmesg, is where it actually gets attached!


+--+--++
| Paul Goyette | PGP Key fingerprint: | E-mail addresses:  |
| (Retired)| FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+--+--++

Re: Unexpected kernel device dependency for 'vga* at pci?'

[Robert Elz]

Date:Sun, 10 Jul 2016 07:00:11 +0800 (PHT)
From:Paul Goyette 
Message-ID:  

  | While doing this, I've discovered that a radeondrmkmsfb0-based kernel 
  | requires that I retain the
  | 
  | vga* at pci? dev ? func ?
  | 
  | line in the configuration, even though no such device is ever attached.

I saw the exact same problem a month or so ago, but with a system using
integrated intel graphics (core i3 processor).

I didn't bother to mention it as config file inter-dependencies and weirdness
are just "normal" ...

I think I concluded/assumed that the issue may have really related to the

wsdisplay*  at vga? console ?

line that also had to be deleted (there being no vga? at anything left
in the config - or in the console messages on a GENERIC boot) leaving
nothing marked as "console" - whether that's actually true or not I didn't
bother to find out - I put that entry back, and so had to also return the
vga? at .. config, and after that, it all worked.

When it wasn't working, the symptoms were as you described (though I probably 
did less tests.)

kre