Re: [Xen-devel] [Valgrind-developers] [PATCH] valgrind: Support for ioctls used by Xen toolstack processes.

[Bart Van Assche <bvanassche@xxxxxxx>]

On 09/04/12 18:20, Ian Campbell wrote:
> One issue is that the hypercalls which are exlusively used by the
> toolstacks (as opposed to those used by guest operating systems) are
> not considered a stable ABI, since the hypervisor and the lowlevel
> tools are considered a matched pair. This covers the sysctl and
> domctl hypercalls which are a fairly large chunk of the support
> here. I'm not sure how to solve this without invoking a massive
> amount of duplication. Right now this targets the Xen unstable
> interface (which will shortly be released as Xen 4.2), perhaps I can
> get away with deferring this problem until the first change ;-).

Does this mean the Xen interface is not backwards compatible ? If so,
are you sure you want to add support for an unstable API in Valgrind ?

> There are some other wrinkles here I've not been sure how to solve:
> 
> Firstly, di_notify_mmap tries to read from the magic proc device:
>      --20208-- WARNING: Serious error when reading debug info
>      --20208-- When reading debug info from /proc/xen/privcmd:
>      --20208-- can't read file to inspect ELF header
> 
> I've hacked around this with an explicit check for /proc/xen.
> Hopefully someone can point to the right solution.

The changes for avoiding reading debuginfo from /proc/xen/privcmd look
fine to me.

Bart.

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