Re: [Minios-devel] [UNIKRAFT PATCHv4 17/43] plat/include: Define macros for Arm64 to access registers

[Julien Grall <julien.grall@xxxxxxx>]

On 12/07/18 03:41, Wei Chen wrote:
> Hi Julien,
Hi Wei,

> > -----Original Message-----
> > From: Julien Grall <julien.grall@xxxxxxx>
> > Sent: 2018年7月11日 21:16
> > To: Wei Chen <Wei.Chen@xxxxxxx>; minios-devel@xxxxxxxxxxxxxxxxxxxx;
> > simon.kuenzer@xxxxxxxxx
> > Cc: Kaly Xin <Kaly.Xin@xxxxxxx>; nd <nd@xxxxxxx>
> > Subject: Re: [Minios-devel] [UNIKRAFT PATCHv4 17/43] plat/include: Define
> > macros for Arm64 to access registers
> >
> > On 11/07/18 07:28, Wei Chen wrote:
> > > Hi Julien,
> > Hi Wei,
> >
> > > Yes, the only device we're using on Arm is PL011, so it's the only one
> > > user of this today.
> > I meant for outb/inb. Not REG_READ*() helpers. So do you have any users
> > of outb/inb today for Arm?
> Yes, the common code like PCI bus will use it. Even I know the PCI bus
> could not work properly on Arm. But I still want the PCI code can be
> compiled on Arm.
What's the rationale of compiling PCI code if it is wrong? Mostly like 
PCI code will use through 0xcf8/0xcfc that does not have equivalent on 
Arm. Instead, we will need to add support for ECAM.
Anyway that's the maintainers call here. However, you should at least 
not implement outb/inb the way you did. This is a call to misuse them. 
Instead you should implement using BUG() or ASSERT(). So any use of 
those outb will be caught later on.
Cheers,

--
Julien Grall

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