Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64with MCP51 laptops

[Alan Cox]

There is another reason we can't just do a dumb changeover - two actually

#1: Some drivers are using inb_p/outb_p in PCI cases which are going to
cause PCI posting changes. Most are probably just wrong in the first
place but they need hand checking

#2: We've got SMP cases that only 'work' because the odds of splitting
the outb and the following port 0x80 cycle, which locks the bus, are tiny.

That is we've got

		CPU1			CPU2
		main path		irq path
		outb
					outb

		inb 0x80
					inb 0x80

races in one or two spots.
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