Re: supported machines for aarch64

Re: supported machines for aarch64

[Philippe Mathieu-Daudé]

Hi,

On 2/15/21 6:26 AM, ckim@etri.re.kr wrote:
> Hello,
> 
> I tried “qemu-system-arm –machine help” and it gave me 75 machines.
> 
> Then I tried “qemu-system-aarch64 –machine help”, and it gave me almost
> the same result except it had raspi3, sbsa-ref, xlnx-versal-virt and
> xlnx-zcu102 in addition.
> 
> I asked myself, Does this mean most machines work both in 32bit mode and
> 64bit mode and those added 4 machines work only in 64bit mode?

Yes.

> So I tried for integrator machine which is supported both by
> qemu-system-arm and qemu-system-aarch64,
> 
> “qemu-system-arm –machine integrator –cpu help” and “qemu-system-aarch64
> –machine integrator –cpu help”, and this time,
> 
> The cpu list was almost the same(mostly seemd older 32 bit versions) but
> the aarch64 cpu list gave me 3 more cpus (cortex-a53, a57 and a72).

Indeed.

> 
> So I realized the qemu-system-aarch64 can emulate both 32bit and 64bit
> machine and cpu cores – as the document says.

Correct.

> .(it’s still strange “qemu-system-arm –machine help” doesn’t give me
> xlnx-versal-virt in the list, but “qemu-system-arm –machine
> xlnx-versal-virt –cpu help” still gives some machines in the list..)

This is because '-cpu' is processed *before* '-machine', so this works:

$ qemu-system-arm -M adsfafdadsfasdfdafadfasdfa -cpu help
Available CPUs:
  arm1026
  arm1136
  arm1136-r2
  ...

> I started this as a question but found out the answer while writing..

:)

> Thank you and correct me if I’m wrong

Regards,

Phil.

RE: supported machines for aarch64

[ckim]

Hello folks,

These are the machine lists that included cortex-a72 when I gave
qemu-system-aarch64 --machine xxx --cpu help.
(I replaced xxx with all the machine I got from qemu-system-aarch64
--machine help. Of course I used simple script for that. And I remove 'virt'
from the list.)

akita               highbank            midway              netduino2
realview-pb-a8      sx1-v1              xilinx-zynq-a9
ast2500-evb         imx25-pdk           mps2-an385          netduinoplus2
realview-pbx-a9     tacoma-bmc          xlnx-zcu102
ast2600-evb         integratorcp        mps2-an505          none
romulus-bmc         terrier             z2
borzoi              kzm                 mps2-an511          nuri
sabrelite           tosa
canon-a1100         lm3s6965evb         mps2-an521          orangepi-pc
sbsa-ref            verdex
cheetah             lm3s811evb          musca-a             palmetto-bmc
smdkc210            versatileab
collie              mainstone           musca-b1            raspi2
sonorapass-bmc      versatilepb
connex              mcimx6ul-evk        musicpal            raspi3
spitz               vexpress-a15
cubieboard          mcimx7d-sabre       n800                realview-eb
swift-bmc           vexpress-a9
emcraft-sf2         microbit            n810
realview-eb-mpcore  sx1                 witherspoon-bmc

Do they all really support cortex-a72? I ask this because for example, when
I search for the first machine akita on internet, it says it's using PXA255
which ARMv5 chip. But cortex-a72 is ARMv8 chip. Can akita really emulate
cortex-a72?

Thanks!
Chan Kim


> -----Original Message-----
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> Sent: Monday, February 15, 2021 4:38 PM
> To: ckim@etri.re.kr; qemu-discuss@nongnu.org
> Cc: qemu-devel <qemu-devel@nongnu.org>; Markus Armbruster
> <armbru@redhat.com>; Paolo Bonzini <pbonzini@redhat.com>
> Subject: Re: supported machines for aarch64
> 
> Hi,
> 
> On 2/15/21 6:26 AM, ckim@etri.re.kr wrote:
> > Hello,
> >
> > I tried “qemu-system-arm –machine help” and it gave me 75 machines.
> >
> > Then I tried “qemu-system-aarch64 –machine help”, and it gave me
> > almost the same result except it had raspi3, sbsa-ref,
> > xlnx-versal-virt and
> > xlnx-zcu102 in addition.
> >
> > I asked myself, Does this mean most machines work both in 32bit mode
> > and 64bit mode and those added 4 machines work only in 64bit mode?
> 
> Yes.
> 
> > So I tried for integrator machine which is supported both by
> > qemu-system-arm and qemu-system-aarch64,
> >
> > “qemu-system-arm –machine integrator –cpu help” and
> > “qemu-system-aarch64 –machine integrator –cpu help”, and this time,
> >
> > The cpu list was almost the same(mostly seemd older 32 bit versions)
> > but the aarch64 cpu list gave me 3 more cpus (cortex-a53, a57 and a72).
> 
> Indeed.
> 
> >
> > So I realized the qemu-system-aarch64 can emulate both 32bit and 64bit
> > machine and cpu cores – as the document says.
> 
> Correct.
> 
> > .(it’s still strange “qemu-system-arm –machine help” doesn’t give me
> > xlnx-versal-virt in the list, but “qemu-system-arm –machine
> > xlnx-versal-virt –cpu help” still gives some machines in the list..)
> 
> This is because '-cpu' is processed *before* '-machine', so this works:
> 
> $ qemu-system-arm -M adsfafdadsfasdfdafadfasdfa -cpu help Available CPUs:
>   arm1026
>   arm1136
>   arm1136-r2
>   ...
> 
> > I started this as a question but found out the answer while writing..
> 
> :)
> 
> > Thank you and correct me if I’m wrong
> 
> Regards,
> 
> Phil.
> 

Re: supported machines for aarch64

[Peter Maydell]

On Fri, 19 Feb 2021 at 08:05, <ckim@etri.re.kr> wrote:
> These are the machine lists that included cortex-a72 when I gave
> qemu-system-aarch64 --machine xxx --cpu help.

Adding '--machine whatever' to your command line does not change
the output of '--cpu help'. As Philippe says, it happens that
QEMU processes --cpu before --machine, so it handles '--cpu help',
prints the fixed list of supported CPUs, and ignores whether you
passed a valid --machine option or not.

There is no automated way to get QEMU to tell you which CPUs
a particular board model supports.

I recommend that you follow the advice given here
https://qemu.readthedocs.io/en/latest/system/target-arm.html#choosing-a-board-model
for how to choose a board model. (Short answer: if you know
you want to run guest code for a specific board type, use that
board type. Otherwise, use 'virt'.) Then, you should stick with
the default CPU type (ie, do not pass --cpu) for that board,
for all board types *except* 'virt'. For 'virt' you can pass
in the CPU type you want (and the documentation lists which
types it supports).

-- PMM

RE: supported machines for aarch64

[ckim]

Hi Peter Maydell,

Thanks, that made it clearer to me.(actually I was reading the page you mentioned)

Chan Kim

> -----Original Message-----
> From: Peter Maydell <peter.maydell@linaro.org>
> Sent: Friday, February 19, 2021 7:04 PM
> To: Chan Kim <ckim@etri.re.kr>
> Cc: Philippe Mathieu-Daudé <philmd@redhat.com>; qemu-discuss <qemu-
> discuss@nongnu.org>; Paolo Bonzini <pbonzini@redhat.com>; qemu-devel
> <qemu-devel@nongnu.org>; Markus Armbruster <armbru@redhat.com>
> Subject: Re: supported machines for aarch64
> 
> On Fri, 19 Feb 2021 at 08:05, <ckim@etri.re.kr> wrote:
> > These are the machine lists that included cortex-a72 when I gave
> > qemu-system-aarch64 --machine xxx --cpu help.
> 
> Adding '--machine whatever' to your command line does not change the
> output of '--cpu help'. As Philippe says, it happens that QEMU processes -
> -cpu before --machine, so it handles '--cpu help', prints the fixed list
> of supported CPUs, and ignores whether you passed a valid --machine option
> or not.
> 
> There is no automated way to get QEMU to tell you which CPUs a particular
> board model supports.
> 
> I recommend that you follow the advice given here
> https://qemu.readthedocs.io/en/latest/system/target-arm.html#choosing-a-
> board-model
> for how to choose a board model. (Short answer: if you know you want to
> run guest code for a specific board type, use that board type. Otherwise,
> use 'virt'.) Then, you should stick with the default CPU type (ie, do not
> pass --cpu) for that board, for all board types *except* 'virt'. For
> 'virt' you can pass in the CPU type you want (and the documentation lists
> which types it supports).
> 
> -- PMM