Andrew Morton wrote:
Well I queued up a tentative revert patch but then I re-read the changlog:
x86, serial: convert legacy COM ports to platform devices
Make x86 COM ports into platform devices and don't probe for them
if we have PNP.
This prevents double discovery, where a device was found both by
the legacy probe and by 8250_pnp, e.g.,
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
00:02: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
If this actually causes a problem, then the drivers are buggy. We have
standard APIs for checking this stuff...
Turning off legacy serial probing is just a bandaid, the resource bug is
still there [by definition, if double-probing problems exist].
This also means IRDA devices without a UART PNP ID will no longer be
claimed by the serial driver, which might require changes in IRDA
drivers and administration.
This was completely unaddressed, I presume?
In addition to this patch, you may need to configure a setserial init
script, e.g., /etc/init.d/setserial, so it doesn't poke legacy UART
stuff back in. On Debian, "dpkg-reconfigure setserial" with the "kernel"
option does this.
So this patch breaks some userspace too?
To force the old legacy probe behavior even when we have PNPBIOS or
ACPI, load the new legacy_serial module (or build 8250 static) with
the "legacy_serial.force" option.
So 7e92b4fc345f5b6f57585fbe5ffdb0f24d7c9b26 fixed a bunch of longstanding
nasties while breaking Sebastien's machine (at least).
We of course want the best of both worlds here, so I'll keep the revert
patch in -mm for a while, see what happens. Although I can't immediately
see any way in which this can be fixed...
I see VERY few positives, a whole lot of trouble, and a couple band-aids.
Jeff
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