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

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Julien,

> -----Original Message-----
> From: Julien Grall <julien.grall@xxxxxxx>
> Sent: 2018年7月9日 18:29
> 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 09/07/18 10:37, Wei Chen wrote:
> > Hi Julien,
> 
> Hi Wei,
> 
> >> -----Original Message-----
> >> From: Julien Grall <julien.grall@xxxxxxx>
> >> Sent: 2018年7月8日 6:13
> >> 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
> >>
> >> Hi,
> >>
> >> On 07/06/2018 10:03 AM, Wei Chen wrote:
> >>> In the progress of Arm64 system initialization, we need to access
> >>> the system registers to configure some CPU features, we also need
> >>> to access device registers to make device work. So in this patch,
> >>> we define macros to access device registers and system registers.
> >>>
> >>> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
> >>> ---
> >>>    plat/common/include/arm/arm64/cpu.h | 72 +++++++++++++++++++++++++++++
> >>>    plat/common/include/arm/cpu.h       | 46 ++++++++++++++++++
> >>>    plat/common/include/cpu.h           |  4 +-
> >>>    3 files changed, 121 insertions(+), 1 deletion(-)
> >>>    create mode 100644 plat/common/include/arm/arm64/cpu.h
> >>>    create mode 100644 plat/common/include/arm/cpu.h
> >>>
> >>> diff --git a/plat/common/include/arm/arm64/cpu.h
> >> b/plat/common/include/arm/arm64/cpu.h
> >>> new file mode 100644
> >>> index 0000000..7c79462
> >>> --- /dev/null
> >>> +++ b/plat/common/include/arm/arm64/cpu.h
> >>> @@ -0,0 +1,72 @@
> >>> +/* SPDX-License-Identifier: BSD-3-Clause */
> >>> +/*
> >>> + * Authors: Wei Chen <wei.chen@xxxxxxx>
> >>> + *
> >>> + * Copyright (c) 2018, Arm Ltd. All rights reserved.
> >>> + *
> >>> + * Redistribution and use in source and binary forms, with or without
> >>> + * modification, are permitted provided that the following conditions
> >>> + * are met:
> >>> + *
> >>> + * 1. Redistributions of source code must retain the above copyright
> >>> + *    notice, this list of conditions and the following disclaimer.
> >>> + * 2. Redistributions in binary form must reproduce the above copyright
> >>> + *    notice, this list of conditions and the following disclaimer in the
> >>> + *    documentation and/or other materials provided with the 
> >>> distribution.
> >>> + * 3. Neither the name of the copyright holder nor the names of its
> >>> + *    contributors may be used to endorse or promote products derived
> from
> >>> + *    this software without specific prior written permission.
> >>> + *
> >>> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS
> >> IS"
> >>> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
> >> THE
> >>> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
> >> PURPOSE
> >>> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS
> >> BE
> >>> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> >>> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> >>> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
> BUSINESS
> >>> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
> IN
> >>> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
> >>> OTHERWISE)
> >>> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
> >> THE
> >>> + * POSSIBILITY OF SUCH DAMAGE.
> >>> + *
> >>> + * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
> >>> + */
> >>> +
> >>> +#include <inttypes.h>
> >>> +
> >>> +#define REG_READ8(addr)            \
> >> The naming is slightly confusing, you don't really now which register
> >> you are reading. How about renaming them to ioread. This would make
> >> clearer that you do io access.
> >
> > That's fine with me. About this name, I have been commented in
> > different projects with different contents : )
> > Some guys said, you don't have IO instructions, why you use io as
> > Prefix ; )
> 
> IO are not only accessed via instructions (e.g outb/inb), they can also
> be memory mapped as it is on Arm.
> 
> With the wording "reg", it is not clear whether you are accessing the
> system register or mmio register.
> 
> But then you implement outb/inb below that does not make sense for Arm ;).
> 

Yes, that's right : ) I implement outb/inb here just to make some common
code happy, because they are using x86's inb/outb API by default. I don't
want to make #if defined (__aarch64__) everywhere.

I will discuss with Simon about this. Maybe we can design some interfaces
for IO, just like uk_ioread/uk_iowrite.

> Cheers,
> 
> --
> Julien Grall
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