path: root/Documentation
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authorBjorn Helgaas <bjorn.helgaas@hp.com>2007-05-08 00:36:07 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:15:23 -0700
commit7e92b4fc345f5b6f57585fbe5ffdb0f24d7c9b26 (patch)
treea8e9dac38a9c8dd22bd182c13e2ae0e6d32bd729 /Documentation
parentd0d4f69bb65a8c1c1430c577a583632709b874c6 (diff)
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 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. 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. 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. [akpm@linux-foundation.org: fix makefiles] Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Keith Owens <kaos@ocs.com.au> Cc: Len Brown <lenb@kernel.org> Cc: Adam Belay <ambx1@neo.rr.com> Cc: Matthieu CASTET <castet.matthieu@free.fr> Cc: Jean Tourrilhes <jt@hpl.hp.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Ville Syrjala <syrjala@sci.fi> Cc: Russell King <rmk+serial@arm.linux.org.uk> Cc: Samuel Ortiz <samuel@sortiz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index fa885174fd7..bebebe4fd46 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -816,6 +816,11 @@ and is between 256 and 4096 characters. It is defined in the file
lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
Format: addr:<io>,irq:<irq>
+ legacy_serial.force [HW,IA-32,X86-64]
+ Probe for COM ports at legacy addresses even
+ if PNPBIOS or ACPI should describe them. This
+ is for working around firmware defects.
llsc*= [IA64] See function print_params() in