http://bugzilla.kernel.org/show_bug.cgi?id=8572
Summary: Dell OptiPlex GX240, ACPI and IO-APIC
Kernel Version: 2.6.21.3
Status: NEW
Severity: normal
Owner: [EMAIL PROTECTED]
Submitter: [EMAIL PROTECTED]
Most recent kernel where this bug did *NOT* occur: None
Distribution: Debian 4.0r0 ("Etch")
Hardware Environment: Dell OptiPlex GX240, Pentim IV 1.7GHz
Software Environment: Linux 2.6.21.3 from kernel.org
Problem Description: When ACPI is disabled but IO-APIC
is enabled, the USB ports on the front panel of
Dell OptiPlex GX240 very slowly. (Dell OptiPlex GX240
is in the ACPI blacklist so ACPI gets set up only
by acpi=ht.) This results in very slow USB performance.
Copying a few photos from an USB-enabled digital camera
takes five to six times longer compared to the performance
when the camera is connected to one ofthe USB ports on
the rear panel.
If Dell OptiPlex GX240 had not been in the ACPI blacklist,
this problem would show up only with kernels without ACPI
compiled in.
In addition, I wrote a patch which implements an IO-APIC
blacklist and disables IO-APIC on Dell Optiplex GX240
if ACPI is not enabled.
Please see the following threads for more information:
http://marc.info/?t=118079385400003&r=1&w=2
http://marc.info/?t=117897881900001&r=1&w=2
Steps to reproduce: Find a Dell OptiPlex GX240 and
boot Linux without anything appended to the kernel
command line. Notice that the USB ports on the front
panel work very slowly whereas the ports on the rear
panel work normally. Boot with "acpi=force" *OR* "noapic"
appended to the command line and notice that the USB
ports on the front panel start work at normal speed.
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