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Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 6
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit |
Date: |
Tue, 30 Jun 2020 15:45:03 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 6/30/20 3:36 PM, Thomas Huth wrote:
> On 30/06/2020 13.17, Aleksandar Markovic wrote:
>>
>>
>> уторак, 30. јун 2020., Philippe Mathieu-Daudé <f4bug@amsat.org
>> <mailto:f4bug@amsat.org>> је написао/ла:
>>
>> On 6/30/20 1:01 PM, Aleksandar Markovic wrote:
>> >
>> >
>> > уторак, 30. јун 2020., Philippe Mathieu-Daudé <f4bug@amsat.org
>> <mailto:f4bug@amsat.org>
>> > <mailto:f4bug@amsat.org <mailto:f4bug@amsat.org>>> је написао/ла:
>> >
>> > On Tue, Jun 30, 2020 at 12:52 PM Philippe Mathieu-Daudé
>> > <f4bug@amsat.org <mailto:f4bug@amsat.org>
>> <mailto:f4bug@amsat.org <mailto:f4bug@amsat.org>>> wrote:
>> > >
>> > > On 6/30/20 12:48 PM, Aleksandar Markovic wrote:
>> > > >
>> > > >
>> > > > уторак, 30. јун 2020., Philippe Mathieu-Daudé
>> <f4bug@amsat.org <mailto:f4bug@amsat.org>
>> > <mailto:f4bug@amsat.org <mailto:f4bug@amsat.org>>
>> > > > <mailto:f4bug@amsat.org <mailto:f4bug@amsat.org>
>> <mailto:f4bug@amsat.org <mailto:f4bug@amsat.org>>>> је написао/ла:
>> > > >
>> > > > Hi,
>> > > >
>> > > > Following Jiaxun Yang's patch and discussion:
>> > > > https://patchwork.kernel.org/patch/11416915/
>> <https://patchwork.kernel.org/patch/11416915/>
>> > <https://patchwork.kernel.org/patch/11416915/
>> <https://patchwork.kernel.org/patch/11416915/>>
>> > > > <https://patchwork.kernel.org/patch/11416915/
>> <https://patchwork.kernel.org/patch/11416915/>
>> > <https://patchwork.kernel.org/patch/11416915/
>> <https://patchwork.kernel.org/patch/11416915/>>>
>> > > >
>> > > > - Rename the current machine as 'malta-virt' (keeping
>> > 'malta' aliased)
>> > > > Suggestions for better names are welcome, maybe
>> > 'malta-unreal' or
>> > > > 'malta-unleashed' instead?
>> > > > - Add 'malta-phys' which respects hardware
>> restrictions (on
>> > RAM so far)
>> > > > - Unleash 'malta-virt' to allow more than 2GB on
>> 64-bit
>> > > >
>> > > > Philippe Mathieu-Daudé (7):
>> > > > hw/mips/malta: Trivial code movement
>> > > > hw/mips/malta: Register the machine as a TypeInfo
>> > > > hw/mips/malta: Rename 'malta' machine as
>> 'malta-virt'
>> > > > hw/mips/malta: Introduce
>> MaltaMachineClass::max_ramsize
>> > > > hw/mips/malta: Introduce the 'malta-phys' machine
>> > > > hw/mips/malta: Verify malta-phys machine uses
>> correct DIMM
>> > sizes
>> > > > hw/mips/malta: Allow more than 2GB on 64-bit
>> malta-virt
>> > > >
>> > > > hw/mips/malta.c | 121
>> > +++++++++++++++++++++++++++++++++++++++---------
>> > > > 1 file changed, 99 insertions(+), 22 deletions(-)
>> > > >
>> > > > --
>> > > >
>> > > >
>> > > >
>> > > > Thank you, Philippe, for providing this series.
>> > > >
>> > > > However, in previous discussion on the patch you mention
>> above, I
>> > > > already expressed serious reservations on the approach
>> taken in that
>> > > > patch. These reservations stay today too.
>> > > >
>> > > > There is nothing qualitatively different between the
>> original
>> > patch and
>> > > > this series. Naming and related stuff are just cosmetic
>> issues.
>> > >
>> > > OK, what about considering all patches except the last one?
>> > > So we can run firmware on a real Malta board, not the QEMU
>> > > imaginary one (in the discussion you said QEMU should
>> respect
>> > > real hardware, which I agree).
>> > >
>> > > >
>> > > > The good thing about this series is that one can apply it
>> > dowstream, if
>> > > > one finds it useful. However, it is not suitable for
>> upstreaming
>> >
>> > IOW, what is missing to have this series (except the last
>> patch)
>> > accepted upstream?
>> >
>> >
>> > It is not what is missing, but was already is in the series that
>> makes
>> > it not suitable for upstreaming. The very concept of the series is
>> > problematic.
>>
>> What is the series is not suitable for upstream? Can you point to
>> patch and code please? How would you conceptually resolve the
>> problem?
>>
>>
>> The answer is already in the original thread on the original patch.
>>
>> The problem is artificialy imposed:
>>
>> One needs a feature not present in the physical system. The solution
>> is not in creating "virtual" upgrade - this violates the basic
>> foundation if QEMU.
>>
>> If the feature is missing, the optimal solution would be emulating the
>> physical solution that has that feature.
>>
>> In some rare cases (that should be avoided as mush as possible), and
>> for really good reasons, we can create an emulation of some imagined
>> hardware that was never designed let alone built - there are a couple
>> of examples in other targets.
>>
>> But extending the emulation of existing physical system with
>> non-existing features is not acceptable.
>
> Interesting statement. I suggest to include the following patch in your
> next mips pull request to avoid that mips users spoil their machines
> with virtual-only features:
>
> diff a/default-configs/mips-softmmu-common.mak
> b/default-configs/mips-softmmu-common.mak
> --- a/default-configs/mips-softmmu-common.mak
> +++ b/default-configs/mips-softmmu-common.mak
> @@ -6,10 +6,10 @@ CONFIG_SEMIHOSTING=y
> CONFIG_ISA_BUS=y
> CONFIG_PCI=y
> CONFIG_PCI_DEVICES=y
> +CONFIG_VIRTIO_PCI=n
> CONFIG_VGA_ISA=y
> CONFIG_VGA_ISA_MM=y
> CONFIG_VGA_CIRRUS=y
> -CONFIG_VMWARE_VGA=y
> CONFIG_SERIAL=y
> CONFIG_SERIAL_ISA=y
> CONFIG_PARALLEL=y
>
> ;-)
>
> No, seriously, as far as I can tell, QEMU was never in that "we strictly
> only emulate real hardware" camp, even the homepage talks about
> "virtualizer".
>
> But introducing a separate machine for this feature sounds a little bit
> excessive for me, too. What about introducing a machine property for the
> max-ram-size? With the default value, the machine could restrict the ram
> sizes to the values that are possible with the real hardware, and only
> if the (advanced) user tweaks the property, it would be possible to set
> bigger values. Just my 0.02 €.
>
> Thomas
>
>
> PS: Why does mips use CONFIG_VMWARE_VGA=y at all? Is VMWARE also
> available for mips?
>
> PPS: Why is mips still not using proper Kconfig settings yet?
Related to "ACPI + ICH9 + PIIX4" interdependence with X86. Fixing MIPS
would break X86. We can not break X86 (and there is little interest from
enterprise X86 on solving MIPS emulation problems).
Then I consumed all the time my manager granted me to work on it, so
it is very low in my list. If someone else want to do it, help welcomed.
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, (continued)
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Thomas Huth, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit,
Philippe Mathieu-Daudé <=
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Philippe Mathieu-Daudé, 2020/06/30
- Re: [PATCH 0/7] hw/mips/malta: Rework to allow more than 2GB of RAM on 64-bit, Aleksandar Markovic, 2020/06/30