Re: [Qemu-devel] [RFC PATCH] hw/arm/virt: use variable size of flash device to save memory

[Markus Armbruster <armbru@redhat.com>]

Laszlo Ersek <lersek@redhat.com> writes:

> On 03/26/19 17:39, Markus Armbruster wrote:
>> Laszlo Ersek <lersek@redhat.com> writes:
>
>>> With the dynamic sizing in QEMU (which, IIRC, I had originally
>>> introduced still in the 1MB times, due to the split between the
>>> executable and varstore parts), both the 1MB->2MB switch, and the
>>> 2MB->4MB switch in the firmware caused zero pain in QEMU. And right now,
>>> 4MB looks like a "sweet spot", with some elbow room left.
>> 
>> Explicit configuration would've been exactly as painless.  Even with
>> pflash sizes restricted to powers of two.
>
> I wrote the patch that ended up as commit 637a5acb46b3 -- with your R-b
> -- in 2013. I'm unsure if machine type properties existed back then, but
> even if they did, do you think I knew about them? :)
>
> You are right, of course; it's just that we can't tell the future.

True!  All we can do is continue to design as well as we can given the
information, experience and resources we have, and when the inevitable
design mistakes become apparent, limit their impact.

Some of the things we now consider mistakes we just didn't see.  Others
we saw (e.g. multiple pflash devices, unlike physical hardware), but
underestimated their impact.

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