Re: [PATCH] STM32F100: support different density lines

[Alexandre IOOSS]

On 6/20/23 00:18, Lucas Villa Real wrote:
> This patch adds support for the emulation of different density lines
> (low, medium, and high). A new class property stm32f100-soc.density=
> has been introduced to allow users to state the desired configuration.
> That property is recognized by a new machine, stm32f1-generic. The SOC
> is configured according to the following:
>
>     density=low       32 KB FLASH, 2 SPIs
>     density=medium   128 KB FLASH, 2 SPIs
>     density=high     512 KB FLASH, 3 SPIs
>
> With this code change we should be able to introduce richer features
> to STM32F100, such as support for FSMC (so that a machine with more
> RAM capacity can be properly emulated). FSMC is supported on high
> density line devices only.

Thanks a lot for the patches!

STM32 families look very similar to each other, it makes great sense to 
take a generic approach rather than bloating QEMU with many machines.

You patch proposes to create a "stm32f1-generic" machine. I believe we 
should rather name this machine "stm32f100-generic":
  - STM32F101 has a XL-density line, STM32F100 does not have a 
XL-density line.
  - STM32F100 high density line does not have the same maximum SRAM 
size, timers, USART numbers, clock frequencies and CEC peripherals as 
the STM32F101 high density line.

Regarding the stm32vldiscovery machine, I am not against deprecating it 
if we warn users to use stm32f100-generic with density=medium. This 
makes sense as the development board does not add anything more than 
just some buttons and LED.
Maybe "stm32vldiscovery" could become an alias for stm32f100-generic 
machine ?
@Alistair: Do you have an opinion on aliasing the old machine? Is this 
something common in QEMU?

In the long run, we should maybe rename "stm32f100-soc.c" to 
"stm32f1-soc.c" and add another class property to choose the sub-family. 
This would highly reduce potential code duplication.
STM32F1 machines could take this structure:
 - stm32f100-generic machine
   - stm32f1-soc.family=f100 stm32f1-soc.density=low
   - stm32f1-soc.family=f100 stm32f1-soc.density=medium
     (alias stm32vldiscovery)
   - stm32f1-soc.family=f100 stm32f1-soc.density=high
 - stm32f101-generic machine
   - stm32f1-soc.family=f101 stm32f1-soc.density=low
   - stm32f1-soc.family=f101 stm32f1-soc.density=medium
   - stm32f1-soc.family=f101 stm32f1-soc.density=high
   - stm32f1-soc.family=f101 stm32f1-soc.density=xl
 - stm32f102-generic machine
   - stm32f1-soc.family=f102 stm32f1-soc.density=low
   - stm32f1-soc.family=f102 stm32f1-soc.density=medium
 - stm32f103-generic machine
   - stm32f1-soc.family=f103 stm32f1-soc.density=low
   - stm32f1-soc.family=f103 stm32f1-soc.density=medium
     (alias stm32-nucleo-f103rb)
   - stm32f1-soc.family=f103 stm32f1-soc.density=high
   - stm32f1-soc.family=f103 stm32f1-soc.density=xl
@Alistair: Would such modification make also sense regarding stm32f2 and 
stm32f4 families?

Thanks,
--
Alexandre

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