Messages in this thread | | | Date | Thu, 14 Mar 2002 16:11:25 -0800 (PST) | From | John Heil <> | Subject | Re: IO delay, port 0x80, and BIOS POST codes |
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On Fri, 15 Mar 2002, David Golden wrote:
> Date: Fri, 15 Mar 2002 00:12:42 +0000 > From: David Golden <david.golden@oceanfree.net> > To: linux-kernel@vger.kernel.org > Subject: Re: IO delay, port 0x80, and BIOS POST codes > > On Thursday 14 March 2002 22:55, Alan Cox wrote: > > > > We've got one. Its 0x80. It works everywhere with only marginal non > > problematic side effects > > I've always liked POST cards. They could hypothetically be useful > for kernel development,too - who hasn't wanted a low-level > single-asm-instruction status output from a running system at one time or > another , independent of any other output mechanisms? > > OK it's a single byte, but it's still nice... That's two whole hex digits! > DE... AD... BE... EF... !
Any number of consecutive bits and a target I/O address can be very useful.
I do it regularly for embedded kernel hacking... harmless I/O, picked up by your logic analyzer.
Only drawback is it adds pathlength which can impact realtime if you get excessive.
Johnh
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- ----------------------------------------------------------------- John Heil South Coast Software Custom systems software for UNIX and IBM MVS mainframes 1-714-774-6952 johnhscs@sc-software.com http://www.sc-software.com -----------------------------------------------------------------
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