Re: [Qemu-devel] [PATCH] configure: Support QEMU cross-compiling for ARM64 host

[Anup Patel <anup.patel@linaro.org>]

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On 8 January 2013 17:38, Peter Maydell <peter.maydell@linaro.org> wrote:

> On 8 January 2013 11:05, Anup Patel <anup.patel@linaro.org> wrote:
> > diff --git a/configure b/configure
> > index fe18ed2..0bfb8bb 100755
> > --- a/configure
> > +++ b/configure
> > @@ -366,6 +366,8 @@ elif check_define __s390__ ; then
> >    fi
> >  elif check_define __arm__ ; then
> >    cpu="arm"
> > +elif check_define __aarch64__ ; then
> > +  cpu="arm64"
>
> This should be "aarch64"...
>
> >  elif check_define __hppa__ ; then
> >    cpu="hppa"
> >  else
> > @@ -388,6 +390,9 @@ case "$cpu" in
> >    armv*b|armv*l|arm)
> >      cpu="arm"
> >    ;;
> > +  arm64|aarch64)
> > +    cpu="arm64"
> > +  ;;
>
> ...and this should just be
>       aarch64)
>           cpu="aarch64"
>      ;;
>
> Here's the rationale for that naming...
>
> So, to start off with, the official ARM terminology goes:
>  * ARMv8 is the new version of the architecture, covering both
>    32 and 64 bit systems. (v7 is the most recent public arch
>    version and is 32 bit only.) There may well be a v9 in future.
>  * AArch64 is the 64 bit operating mode of a 64-bit aware v8
>    core. (AArch32 is the corresponding 32 bit operating mode.)
>    The core can transition between these at exception boundaries.
>  * A64 is the instruction set visible in AArch64. A32 and T32
>    are the 'classic' ARM and Thumb(2) instruction sets visible in
>    AArch32. NB that v8 includes some new stuff even in A32/T32
>    (eg crypto extensions, some extensions to Neon, etc).
>  * arm64 is what the kernel port is called, since Linus doesn't
>    much like any of the above :-) Note that 'uname -m' still
>    says "aarch64", and the gcc triplet uses "aarch64". Only
>    kernel devs looking at source filenames see 'arm64'.
>
> So, QEMU names:
> For the target architecture name (ie what comes out in the
> qemu-foo and qemu-system-foo binary names) we generally use
> the same name that 'uname -m' produces on those machines. In
> this case that would be "aarch64", hence my suggested changes.
>

Agree with your suggestion. I will update the patch accordingly.


>
> The translator sources (as and when we implement a
> TCG QEMU target for this) should live under the existing target-arm.
> We will probably want to put the A64 decoder in its own file,
> ie target-arm/translate-a64.c.
>
> [Big-endian would be aarch64_be, but let's not go there.]
>
>
> Also, I suspect this isn't the only thing that will be required.
> Presumably for an aarch64 build of QEMU we want to use
> the 64 bit kernel KVM headers, which means we need to import
> them. Since neither ARM 32 or 64 bit KVM has landed upstream
> yet those parts are definitely not going to be ready for upstream
> qemu just yet. Similarly the configure check for whether we can
> set CONFIG_KVM needs to accept "target cpu is arm and
> host cpu is aarch64", otherwise we won't enable KVM at all.
>

Yes. This patch only tries to make sure that the configure step falls
through and
at-least QEMU cross-compilation starts.
(assuming we have provided the QEMU dependencies such as zlib, glib-2.0,
etc.)


>
> -- PMM
>

--Anup

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