Re: Can we kill f inb_p, outb_p and other random I/O on port 0x80, in 2.6?
From: bill davidsen
Date: Tue Sep 23 2003 - 13:52:09 EST
In article <20030922215432.GE29869@xxxxxxxxxxxxxxxxxx>,
Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote:
| linux@xxxxxxxxxxx writes:
| > > So can we gradually kill inb_p, outb_p in 2.6? An the other
| > > miscellaneous users of I/O port 0x80 for I/O delays?
| > Actually, It's not easy. The issue got debated a lot a few years ago.
| > A read is also acceptable, and allows a few more ports to be
| > potentially used, but that corrupts %al and thus bloats the code.
| It bloats the code a lot less than udelay() calls or any other
| solution which keeps the delay!
| In the worst case, the bloat from a read _should_ be two bytes: "push
| %eax; inb $80,%al; pop %eax". Whereas a call to udelay is 5 bytes,
| for a call instruction.
Isn't one of the benefits of a rethink not to use any i/o bus cycles?
bill davidsen <davidsen@xxxxxxx>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.
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