Date: Sun, 28 Jun 1998 21:01:19 +0800 From: Peter Wemm <peter@netplex.com.au> To: Zach Heilig <zach@gaffaneys.com> Cc: Mike Smith <mike@smith.net.au>, bde@zeta.org.au, current@FreeBSD.ORG Subject: Re: ppbus is broken. Message-ID: <199806281301.VAA07986@spinner.netplex.com.au> In-Reply-To: Your message of "Sun, 28 Jun 1998 04:54:53 EST." <19980628045453.B650@znh.org.>
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Zach Heilig wrote:
> BTW, I just tried this again (with a fairly recent [june 25] kernel).
> relevant kernel config lines:
>
> controller ppbus0
> device nlpt0 at ppbus?
> controller ppc0 at isa? port? tty irq 7 vector ppcintr
>
> detected as:
>
> ppc0 at 0x378 irq 7 on isa
> ppc0: Generic chipset in EPP mode (EPP 1.9)
> nlpt0: <generic printer> on ppbus 0
> nlpt0: Interrupt-driven port
>
> I can't say for sure that it is fixed, but at least one pdf that used get hos
ed
> comes out properly.
It's a real shame that the 'tty', 'bio', 'net' flags and the 'vector
xxxintr' are required. It's quite a simple change to config(8) and struct
isa_device and isa.c to enable isa drivers to register their own interrupt
handler and mask at probe time.
The best part is that it can be done incrementally.. We can add an
id_maskptr field, and have config generate an single 'isa_devtab' rather
than an 'isa_devtab_bio', 'isa_devtab_net', etc. If the mask is specified
in the config file, it would be used to initialize the field. The driver
can change this at probe time, and isa.c will automatically use it.
It would then become:
controller ppc0 at isa? port? irq 7
but the old specification would still be accepted just fine (but would
essentially be ignored).
I don't know how this fits in with the future plans for interrupt
registration etc, but it's a low impact change that can be gradually
taken advantage of in drivers. This will become more of an issue with
CAM, since it's driver interrupts are masked by 'cam' rather than 'bio',
and it's very easy to get subtle (but very destructive) problems if the
user 'forgets' to change all the 'bio' flags to 'cam'. It would be better
if it wasn't required and was essentially ignored. The device driver
knows this information best, there's no need to duplicate it in the config
file.
Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au> Netplex Consulting
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