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Re: [Xen-devel] hypercall_xlat_continuation()

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] hypercall_xlat_continuation()
From: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
Date: Fri, 22 May 2009 14:58:52 -0700
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>
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Ok. Even if I can't make it clearer, at least I'll add few lines of comments explaining what's going on, after (and if) I figure it out.

Jan,

It seems assumption is made that a 64bit dom0 will not have a 32bit app making hypercall?

BUG_ON(*reg != (unsigned int)*reg);  <====

can you please explain the rationale? Also, can you please comment on other checks, dwiddling with mask, setting *id to *reg value, etc. in this function?


thanks,
Mukesh (starting a new campaign against overuse of ## macros in xen)




Keir Fraser wrote:
Jan wrote it and may still understand it. He's your best hope. If as a
result you think you can make it clearer, please send a patch. :-)

 -- Keir

On 22/05/2009 03:57, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:

Can someone please explain the madness in the else part of this function? The
caller magically passes 2 for mask? Is this already documented anywhere by
chance for mortals like me :).

thanks,
Mukesh

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