From: Ronald G Minnich <rminnich@lanl.gov>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] usb keyboard and mouse?
Date: Thu, 29 Jun 2006 09:02:18 -0600 [thread overview]
Message-ID: <44A3EB7A.708@lanl.gov> (raw)
In-Reply-To: <20060629115531.GB5893@augusta.math.psu.edu>
Dan Cross wrote:
> On Wed, Jun 28, 2006 at 10:31:26PM -0700, Mike Haertel wrote:
>
>>The implementation is chipset dependent. Often what happens is
>>that the chipset recognizes an I/O request to port 0x60 or 0x64 and
>>aborts the request with an SMI (system management interrupt). This
>>is a *very* non-maskable interrupt (more non-maskable than NMI...)
>>that causes the processor to save pretty much all its register state
>>in a special memory area, and jump to a handler in the system BIOS.
>>The BIOS SMI handler examines the saved register state, figures out
>>what the OS was trying to do, runs a software model of the PS/2
>>keyboard controller's state, chats with the USB keyboard, formulates
>>an appropriate response, emulates the I/O instruction the OS was
>>trying to do, and resumes execution of the OS at the instruction
>>following the I/O instruction.
>>
>>Some chipsets might do it directly in hardware rather than using
>>the SMI+BIOS strategy.
>
>
> Dear Lord! At what point is a chicken sacrificed in this process?
>
> - Dan C.
>
well, it does get better. On the GX2, the BIOS is a message-passing
microkernel that lives in SMI. I am not making this up.
ron
next prev parent reply other threads:[~2006-06-29 15:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-29 5:31 Mike Haertel
2006-06-29 8:23 ` Charles Forsyth
2006-06-29 11:55 ` Dan Cross
2006-06-29 15:02 ` Ronald G Minnich [this message]
2006-06-29 23:50 ` Charles Forsyth
-- strict thread matches above, loose matches on Subject: below --
2006-06-26 18:50 ISHWAR RATTAN
2006-06-26 19:22 ` Francisco J Ballesteros
2006-06-27 0:19 ` geoff
2006-06-28 15:48 ` Artem Letko
2006-06-28 17:01 ` Francisco J Ballesteros
2006-06-28 23:02 ` C H Forsyth
2006-06-28 23:21 ` Ronald G Minnich
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