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Re: [Xen-devel] Changing semantics of ioperm() on Xen x86-64?

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Changing semantics of ioperm() on Xen x86-64?
From: Nivedita Singhvi <niv@xxxxxxxxxx>
Date: Tue, 18 Apr 2006 16:36:20 -0700
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Ian Pratt wrote:
As part of the Xen x86-64 Linux port, we've changed the ioperm() syscall to always modify the IOPL instead of actually modifying the IO bitmap in the TSS like we do on x86-32. Is there a particular reason for doing this?

I don't believe so. io bitmap support was added to the hypervisor and
the corresponding ioperm support got added on i386, but was never
carried across to x86_64.

We would definitely benefit from someone doing a code review of x86_64
with a view to unifying as many of the xen patches with i386 as
possible. There's certainly some needless/unhelpful divergence.


Above issue was caught by a LTP test case failure, btw...


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