Re: [Qemu-devel] [PATCH 3/6] hypertrace: [*-user] Add QEMU-side proxy to "guest_hypertrace" event

From: Eric Blake <eblake@redhat.com>
To: "Lluís Vilanova" <vilanova@ac.upc.edu>, qemu-devel@nongnu.org
Cc: Riku Voipio <riku.voipio@iki.fi>, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 3/6] hypertrace: [*-user] Add QEMU-side proxy to "guest_hypertrace" event
Date: Fri, 5 Aug 2016 11:23:29 -0600	[thread overview]
Message-ID: <57A4CB91.6050405@redhat.com> (raw)
In-Reply-To: <147041637969.2523.4570342042982870131.stgit@fimbulvetr.bsc.es>

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On 08/05/2016 10:59 AM, Lluís Vilanova wrote:
> QEMU detects when the guest uses 'mmap' on hypertrace's control channel
> file, and then uses 'mprotect' to detect accesses to it, which are used
> to trigger traceing event "guest_hypertrace".

s/traceing/tracing/

I'll probably leave the technical review to others, though

> +++ b/bsd-user/mmap.c
> @@ -21,6 +21,7 @@
>  #include "qemu.h"
>  #include "qemu-common.h"
>  #include "bsd-mman.h"
> +#include "hypertrace/user.h"
>  
>  //#define DEBUG_MMAP
>  
> @@ -407,6 +408,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
>          }
>      }
>   the_end1:
> +    hypertrace_guest_mmap(fd, (void *)g2h(start));

Why is the cast to void* needed?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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