Re: [Valgrind-developers] Valgrind on ARM, again

[John R. <joh...@gm...>]

On 20/02/2008, Tom Hughes <to...@co...> wrote:
> In message <996...@ma...>
>         John Ripley <joh...@gm...> wrote:
>
> > I realise this gets brought up often, but I'm thinking of having a
> > decent go at getting at least ARMv4 support into Valgrind. I know that
> > there are possibly some legal issues but:
> >
> > * I have never clicked through or signed an agreement not to develop
> > cores or models for ARM.
> > * The ARM reference manual (2nd ed) I have on my desk here doesn't
> > have that agreement.
> > * No datasheet I've downloaded in the past had that agreement.
> > * It seems to have only appeared recently and only on ARMv6/7 data.
> >
> > So I think I'll basically just go ahead regardless and just stay away
> > from anything ARMv6 and up (which the ARM book doesn't cover anyway).
>
> That is the situation as I understand it, yes. I too have an ARMv4
> data book at home that I purchased from a book shop without entering
> into any kind of restrictive agreement.
>
> I think the real question is how useful ARM support will be if we
> can only support relatively old instruction sets.

Very. The vast majority of shipping products with ARM cores in them
are ARMv6 or below, and sadly even the ARMv6 cores are usually running
at most ARMv5 code.

It is also very easy to recompile most applications with -march=armv5,
compared to re-targeting everything for x86-Linux and wrapping
everything in a faked-up environment (e.g missing drivers, etc).

Valgrind for even just ARMv4 would have been incredibly useful to me
for years and even if it was still just ARMv4 would be useful for
years from now :) I've had plenty of bugs disappear when compiled for
x86 and it would have saved a lot of debug time.

> > I just wanted to check if anyone out there had a serious go at it
> > already.
>
> I think the answer to that is yes:
>
> dellow [~/src/valgrind-3] % ls -d VEX/*/*arm*
> VEX/orig_arm/nanoarm       VEX/priv/guest-arm/  VEX/pub/libvex_guest_arm.h
> VEX/orig_arm/nanoarm.orig  VEX/priv/host-arm/

That's a decent start :) I saw the document saying that there was an
old effort to port for ARM, but it's so out of date that it doesn't
compile any more. If the instruction decode/encode is already there,
then that's a HUGE amount of work I won't need to do.

John.