Re: Problem of initialization of platform-ehci-usb in sbsa-ref

[Peter Maydell]

On Mon, 24 Apr 2023 at 13:33, 王宇泉 <wangyuquan1236@phytium.com.cn> wrote:
> As a junior OS engineer, I met a problem of initialization of 
> platform-ehci-usb in sbsa-ref recently.
>
> The result of sbsa-acs(UEFI Shell application) on sbsa-ref shows that 
> "Peripheral: Num of USB controllers: 0".
>
> And I found that the platform-ehci-usb in qemu is a 32-bits DMA device while 
> our sbsa-ref machine does not own
>
> DRAM memory below 4G. It seems like a contradiction point.

This definitely doesn't seem like an intentional thing.
What specifically do you mean by "32-bits DMA device" ?
Is our implementation of this device accidentally not
handling addresses above 4GB? Or is the specification of
the device itself limited to 4GB addresses? Or is this a
guest driver problem?

thanks
-- PMM