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[Xen-ia64-devel] Re: [PATCH]: makes b2-b5 fixed registers

from [Alex Williamson]

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To:	Tristan Gingold <tgingold@xxxxxxx>
Subject:	[Xen-ia64-devel] Re: [PATCH]: makes b2-b5 fixed registers
From:	Alex Williamson <alex.williamson@xxxxxx>
Date:	Sun, 18 Feb 2007 16:53:35 -0700
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On Sun, 2007-02-18 at 16:35 +0100, Tristan Gingold wrote:
> Hi,
> 
> Currently most registers are either fixed (eg: f12-f127) or saved on entry
> in Xen (see minstate.h).
> There are however a few exceptions: ec, lc, b2-b5.  These registers are
> available by the compiler (but not scratch) and saved by save_switch_stack.
> These registers can't be easily written to vcpu_guest_context (unless we
> want to use unwind) which makes implementation of debugger impossible.
> 
> I will work on extending vcpu_guest_context soon.
> During my preliminary work I remaked using objdump that b2-b5 were never used
> by C code.  Therefore I can mark them as fixed without preformance impact.

   Applied.  Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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