On Thu, Jan 18, 2007 at 04:11:42PM +0530, Ashok kumar wrote: > On 1/18/07, Erik Mouw <mouw@xxxxxxxxxxxx> wrote: > >On Thu, Jan 18, 2007 at 03:33:44PM +0530, Ashok kumar wrote: > >> On 1/17/07, Erik Mouw <mouw@xxxxxxxxxxxx> wrote: > >> >There is nothing wrong. Your machine probably traps access to the > >> >keyboard controller and uses SMM (system management mode) to emulate a > >> >real keyboard. > >> > >> i did not get it. can you please explain this?. > >> usb host controller driver itself is not loaded then how it can > >> contact through usb bus? > > > >Because the BIOS emulates it. It does that by trapping access to the > >keyboard controller registers, which cause the CPU to enter SMM. In SMM > >the BIOS handles the USB bus traffic from the keyboard, updates the > >CPU registers as if the CPU really read from the keyboard controller, > >exits SMM after which the CPU resumes normal operation (in the kernel > >keyboard driver). > > > >Note: this is not a normal BIOS call as you would use in DOS. This > >happens at a much lower level. SMM traps are completely transparent to > >the OS (though you can sometimes see lost interrupts). > > ok. thank you. > but, why this is not happening in 2.6.15.5? > any specific reason is there? I don't know. Apparently something else. What was the other kernel that could read data from the USB keyboard? Erik -- They're all fools. Don't worry. Darwin may be slow, but he'll eventually get them. -- Matthew Lammers in alt.sysadmin.recovery
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