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Re: [RFC PATCH 03/14] hw/misc/bcm2835_property: Handle the 'domain state
From: |
Esteban Bosse |
Subject: |
Re: [RFC PATCH 03/14] hw/misc/bcm2835_property: Handle the 'domain state' property |
Date: |
Thu, 24 Oct 2019 11:15:33 +0200 |
User-agent: |
Evolution 3.30.5-1.1 |
El mar, 08-10-2019 a las 11:32 +0200, Philippe Mathieu-Daudé escribió:
> On 9/29/19 9:01 AM, Esteban Bosse wrote:
> > El mié, 04-09-2019 a las 19:13 +0200, Philippe Mathieu-Daudé
> > escribió:
> > > The kernel is happy with this change, so we don't need
> > > to do anything more sophisticated.
> > >
> > > Reviewed-by: Peter Maydell <address@hidden>
> > > Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> > > ---
> > > hw/misc/bcm2835_property.c | 8 ++++++++
> > > 1 file changed, 8 insertions(+)
> > >
> > > diff --git a/hw/misc/bcm2835_property.c
> > > b/hw/misc/bcm2835_property.c
> > > index 399f0d9dd5..d8eb28f267 100644
> > > --- a/hw/misc/bcm2835_property.c
> > > +++ b/hw/misc/bcm2835_property.c
> > > @@ -127,6 +127,14 @@ static void
> > > bcm2835_property_mbox_push(BCM2835PropertyState *s, uint32_t
> > > value)
> > > resplen = 8;
> > > break;
> > >
> > > + case 0x00030030: /* Get domain state */
> > > + qemu_log_mask(LOG_UNIMP,
> > > + "bcm2835_property: 0x%08x get domain
> > > state
> > > NYI\n",
> > > + tag);
> > > + /* FIXME returning uninitialized memory */
> > > + resplen = 8;
> > > + break;
> > > +
> > > case 0x00038002: /* Set clock rate */
> > > case 0x00038004: /* Set max clock rate */
> > > case 0x00038007: /* Set min clock rate */
> >
> > Searching this property in the kernel, I found a lot of properties
> > not
> > implemented.
> > https://github.com/raspberrypi/linux/blob/rpi-4.19.y/include/soc/bcm2835/raspberrypi-firmware.h#L41
> > Are the properties only added when they are necessaries for the
> > standard kernel use?
>
> Yes, the idea is to emulate the bare minimum required to run your
> guest
> code. To test this series I used the closed source kernel provided
> by
> the Raspberry Pi foundation [1] which the one that does the most of
> UNIMP accesses, the Debian trunk one and I build one from [2].
>
> The problem is old kernels don't support the raspi4, and recent
> kernels
> do a lot of property calls to use recent features.
>
> A "property call" is a call from the ARM core to the VideoCore
> firmware,
> like a Remote Procedure Call. The ARM core write some
> arguments/structure to a memory space shared with the VideoCore, use
> a
> MailBox to send a 'property' key to the VideoCore and wait/poll for
> a
> response from the VC. The VC handles the 'property' call, if
> required
> fills the structure in the same memory space the ARM used, then
> reply
> via another MailBox channel to notify the ARM core.
>
> QEMU does not model the VideoCore. Instead we directly fill the
> memory
> from the ARM property call. We fake the VC firmware.
>
> [1]
> https://github.com/raspberrypi/firmware/blob/master/boot/kernel8.img
> [2] https://github.com/raspberrypi/linux/tree/rpi-5.3.y
Thank you very much for all the data Phil.
Now I understood "the idea is to support the bare minimum for the
guest", I thought that the idea was a full HW support, but make sense
it's a lot of work to give full HW support.