Re: [PATCH 9/11] Panic delay fix

From: Zachary Amsden
Date: Wed Feb 07 2007 - 17:24:10 EST


Rusty Russell wrote:
On Wed, 2007-02-07 at 12:35 +0000, Pavel Machek wrote:
Ugh, it sounds like paravirt is more b0rken then I thought. It should
always to the proper delay, then replace those udelays that are not
needed on virtualized hardware with something else.

Just magically defining udelay into nop is broken.

We'd have to audit and figure out what udelays are for hardware and
which are not, but the evidence is that the vast majority of them are
for hardware and not needed for virtualization.

Changing udelay to "hardware_udelay" or something all over the kernel
would have delayed the paravirt_ops merge by an infinite amount 8)

Yes, so I chose the same approach used for b0rken hardware - #define REALLY_SLOW_IO before including headers. It's ugly, but it works without rewriting the entire source base.

Zach
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