From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>, schspa <schspa@gmail.com>,
Kevin Zhao <kevin.zhao@linaro.org>,
Alistair Francis <alistair@alistair23.me>,
QEMU Developers <qemu-devel@nongnu.org>,
Markus Armbruster <armbru@redhat.com>,
qemu-arm <qemu-arm@nongnu.org>
Subject: Re: [PATCH] arm: xlnx-versal: fix virtio-mmio base address assignment
Date: Fri, 5 Feb 2021 11:31:35 +0100 [thread overview]
Message-ID: <aa8ccb78-c977-20fa-a814-4223b678d9c4@amsat.org> (raw)
In-Reply-To: <CAFEAcA9JkTEOhmoFjWYfR5d7ANhKnc9URk89Xe36q7qMVxkMmg@mail.gmail.com>
On 2/5/21 11:03 AM, Peter Maydell wrote:
> On Fri, 5 Feb 2021 at 07:53, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>> Indeed, you found a design issue IMO:
>>
>> Versal creates the "mr-ps-switch" to be explicitly different from
>> the main sysbus memory. TYPE_VIRTIO_MMIO is a SYSBUS device, thus
>> can not be created without being plugged on sysbus.
>> We want TYPE_VIRTIO_MMIO to be TYPE_USER_CREATABLE so we can create
>> it on the command line (like your usage). TYPE_SYSBUS allows such
>> automatic plug it on the main bus, but also maps to main memory.
>
> That was never the design intent for the virtio mmio transport.
> The idea was that the board creates a bunch of transports
> (unconditionally). The user then uses command line options
> to create virtio backends (blk, net, etc) which get plugged
> into the virtio-bus buses that each transport has.
>
> virtio-mmio is not user-creatable for the same reason that
> all devices with MMIO memory regions and IRQ lines are not
> user-creatable -- there's no good command line syntax for
> the user to wire them up, and we don't want the user to have
> to know "on this board address 0x50003000 is a good place to
> put a device, and irq 43 is free".
IOW
1/ virtio-mmio must be sysbus-device,
2/ we can not sysbus-map out of main memory so private container
is incorrect, and Versal can not use "mr-ps-switch"?
>
> thanks
> -- PMM
>
next prev parent reply other threads:[~2021-02-05 10:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 6:58 [PATCH] arm: xlnx-versal: fix virtio-mmio base address assignment schspa
2021-02-04 8:19 ` Philippe Mathieu-Daudé
2021-02-04 9:04 ` schspa
2021-02-05 7:53 ` Philippe Mathieu-Daudé
2021-02-05 10:03 ` Peter Maydell
2021-02-05 10:31 ` Philippe Mathieu-Daudé [this message]
2021-02-05 11:18 ` Peter Maydell
2021-02-05 14:08 ` Edgar E. Iglesias
2021-02-08 5:34 ` schspa
2021-02-08 11:57 ` Laszlo Ersek
2021-02-08 12:59 ` Peter Maydell
2021-02-25 5:36 ` [PATCH v4] virtio-mmio: improve virtio-mmio get_dev_path alog schspa
2021-03-05 11:57 ` Peter Maydell
2021-03-06 2:28 ` Shi Schspa
2021-02-25 6:35 ` [PATCH] arm: xlnx-versal: fix virtio-mmio base address assignment schspa
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