Re: [Qemu-devel] [PATCH 0/6] accel/tcg: Support execution from MMIO and small MMU regions

[Peter Maydell]

On 23 July 2018 at 15:57, Cédric Le Goater <address@hidden> wrote:
> On 07/10/2018 06:00 PM, Peter Maydell wrote:
>> Note for the Xilinx folks: this patchset makes the mmio-exec
>> testcase for running from the SPI flash pass. Cedric: you might
>> like to test the aspeed image you had that relies on execution
>> from an MMIO region too.
>
> I have added a memory region alias at 0x0 on the memory region where
> the first flash device is mapped and all aspeed machines, palmetto,
> romulus, witherspoon booted fine.
>
> More or less 4MB of data access is generated and the slowdown is hardly
> noticeable, around one second on a laptop.
>
> I wonder if I should add a bool option to the machine to activate
> or not the feature ?

I would tend to go with "not" -- if we need the feature then
it's better to run slowly but correctly, and if we don't need
the feature then it doesn't cost us any speed I think.

thanks
-- PMM