Re: [PATCH 08/13] hw/arm/mps3r: Initial skeleton for mps3-an536 board

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 8/2/24 18:07, Cédric Le Goater wrote:
> 
>>>> +/*
>>>> + * The MPS3 DDR is 3GiB, but on a 32-bit host QEMU doesn't permit
>>>> + * emulation of that much guest RAM, so artificially make it smaller.
>>>> + */
>>>> +#if HOST_LONG_BITS == 32
>>>> +#define MPS3_DDR_SIZE (1 * GiB)
>>>> +#else
>>>> +#define MPS3_DDR_SIZE (3 * GiB)
>>>> +#endif
>>>
>>> Generically, can we migrate a VM started on a 32-bit host to a 64-bit
>>> one?
>>
>> I think it's one of those things that in theory is supposed
>> to be possible and in practice nobody tests so it might well
>> not work. At any rate, this is the same thing we do already
>> in mps2-tz.c for the 2GB DRAM those boards have.
> 
> We could have a common helper may be. Aspeed does:
> 
>    /* On 32-bit hosts, lower RAM to 1G because of the 2047 MB limit */
>    #if HOST_LONG_BITS == 32
>    #define ASPEED_RAM_SIZE(sz) MIN((sz), 1 * GiB)
>    #else
>    #define ASPEED_RAM_SIZE(sz) (sz)
>    #endif

Or deprecate system emulation on 32-bit hosts.