Messages in this thread | | | Date | Tue, 24 Jul 2007 15:07:04 -0400 | From | Jeff Garzik <> | Subject | Re: commit 7e92b4fc34 - x86, serial: convert legacy COM ports to platform devices - broke my serial console |
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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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