Re: [Qemu-devel] [PATCH v2 for-4.1] hw/arm/raspi: Diagnose requests for too much RAM

[Philippe Mathieu-Daudé]

Le ven. 29 mars 2019 10:20, Peter Maydell <address@hidden> a
écrit :

> On Thu, 28 Mar 2019 at 21:29, Wainer dos Santos Moschetta
> <address@hidden> wrote:
> >
> >
> > On 03/28/2019 12:29 PM, Peter Maydell wrote:
> > > The Raspberry Pi boards have a physical memory map which does
> > > not allow for more than 1GB of RAM. Currently if the user tries
> > > to ask for more then we fail in a confusing way:
> > >
> > > $ qemu-system-aarch64 --machine raspi3 -m 8G
> > > Unexpected error in visit_type_uintN() at qapi/qapi-visit-core.c:164:
> > > qemu-system-aarch64: Parameter 'vcram-base' expects uint32_t
> > > Aborted (core dumped)
> > >
> > > Catch this earlier and diagnose it with a more friendly message:
> > > $ qemu-system-aarch64 --machine raspi3 -m 8G
> > > qemu-system-aarch64: Requested ram size is too large for this machine:
> maximum is 1GB
> > >
> > > Fixes: https://bugs.launchpad.net/qemu/+bug/1794187
> > > Signed-off-by: Peter Maydell <address@hidden>
> > > ---
> > > Changes v1->v2: use '>', not '>='...
> > >
> > >   hw/arm/raspi.c | 7 +++++++
> > >   1 file changed, 7 insertions(+)
> > >
> > > diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
> > > index 66899c28dc1..fe2bb511b98 100644
> > > --- a/hw/arm/raspi.c
> > > +++ b/hw/arm/raspi.c
> > > @@ -12,6 +12,7 @@
> > >    */
> > >
> > >   #include "qemu/osdep.h"
> > > +#include "qemu/units.h"
> > >   #include "qapi/error.h"
> > >   #include "qemu-common.h"
> > >   #include "cpu.h"
> > > @@ -175,6 +176,12 @@ static void raspi_init(MachineState *machine, int
> version)
> > >       BusState *bus;
> > >       DeviceState *carddev;
> > >
> > > +    if (machine->ram_size > 1 * GiB) {
> > > +        error_report("Requested ram size is too large for this
> machine: "
> > > +                     "maximum is 1GB");
> >
> > 1GB vs 1GiB... maybe the message should display "GiB" to avoid any
> > confusion?
>
> I don't know why we call our #defined constant GiB -- to me
> the unit is GB and I think printing anything else in user
> messages is weird.
>

There was a discussion with Stefan and few other in 2017 the outcome was to
use the explicit IEC standard (and avoid confusion with 1kHz i.e.).

https://en.m.wikipedia.org/wiki/Kibibyte
"The *kibibyte* is a multiple of the unit byte
<https://en.m.wikipedia.org/wiki/Byte> for quantities of digital information
<https://en.m.wikipedia.org/wiki/Information>. The binary prefix
<https://en.m.wikipedia.org/wiki/Binary_prefix> *kibi
<https://en.m.wikipedia.org/wiki/Kibi->* means 210, or 1024; therefore,
1 kibibyte is 1024 bytes. The unit symbol for the kibibyte is *KiB*."


> thanks
> -- PMM
>