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Re: [Minios-devel] [UNIKRAFT PATCHv3 5/7] plat/common: Find and register IRQ for arch_timer





On 9/17/19 9:44 AM, Justin He (Arm Technology China) wrote:
Hi Julien

Hi,

-----Original Message-----
From: Julien Grall <julien.grall@xxxxxxx>
Sent: 2019年9月17日 16:39
To: Justin He (Arm Technology China) <Justin.He@xxxxxxx>; Santiago
Pagani <Santiago.Pagani@xxxxxxxxx>; minios-devel@xxxxxxxxxxxxxxxxxxxx;
Simon Kuenzer <simon.kuenzer@xxxxxxxxx>; Sharan Santhanam
<Sharan.Santhanam@xxxxxxxxx>
Cc: Kaly Xin (Arm Technology China) <Kaly.Xin@xxxxxxx>; Wei Chen (Arm
Technology China) <Wei.Chen@xxxxxxx>; Jianyong Wu (Arm Technology
China) <Jianyong.Wu@xxxxxxx>; nd <nd@xxxxxxx>
Subject: Re: [UNIKRAFT PATCHv3 5/7] plat/common: Find and register IRQ
for arch_timer

On 9/17/19 8:01 AM, Justin He (Arm Technology China) wrote:
Hi Julien (welcome back from holiday 😊 )

Hi,

Thanks :).

-----Original Message-----
From: Julien Grall <julien.grall@xxxxxxx>
Sent: 2019年9月17日 3:53
To: Justin He (Arm Technology China) <Justin.He@xxxxxxx>; Santiago
Pagani <Santiago.Pagani@xxxxxxxxx>; minios-devel@xxxxxxxxxxxxxxxxxxxx;
Simon Kuenzer <simon.kuenzer@xxxxxxxxx>; Sharan Santhanam
<Sharan.Santhanam@xxxxxxxxx>
Cc: Kaly Xin (Arm Technology China) <Kaly.Xin@xxxxxxx>; Wei Chen
(Arm
Technology China) <Wei.Chen@xxxxxxx>; Jianyong Wu (Arm
Technology
China) <Jianyong.Wu@xxxxxxx>
Subject: Re: [UNIKRAFT PATCHv3 5/7] plat/common: Find and register
IRQ
for arch_timer

On 9/16/19 8:52 AM, Justin He (Arm Technology China) wrote:
Hi  Santiago

Hi all,

@Santiago, it is quite difficult to follow the thread when you start
your answer with "COMMENT". May I ask you to configure your e-mail
client to quote properly (i.e >)?

Furthermore, disclaimer footer should be avoided on the mailing list.
You are basically saying this is confidential but you send to everyone
(mailing list are archived)...
OK

It wasn't directed to you ;).


[...]

COMMENT: There is nothing that we would like to do here? Not even
disable the IRQ? As the timer is not stopped, when the counter
overflows
we would get a new interrupt otherwise (although the overflow could
happen in a very very long time, right?)

In previous version, we added a generic_timer_mask_irq() in
generic_timer_irq_handler. But as per the suggestion [1] from Julien,
we
removed it. Besides, we referred to the minios logic at [2], it only called
unmask and mask in block_domain (which is equivalent to unikraft's
generic_timer_cpu_block)

Looking at my comments again, I am not sure where I suggested to
remove
generic_timer_mask_irq()... Can you expand it?
Okay... sorry for my mistakes. I will add generic_timer_mask_irq() back.

FWIW, the two main comments on the previous versions were:
      1) isb() should be added after updating the system register to
ensure that the system system is synchronized
      2) This is common code between arm32 and arm64. But the system
register name are arm64... Accesses should be stub in arch-specific
header so the code can work for both arm32 and arm64.
I renamed plat/common/arm/time.c to plat/common/arm/time_arm64.c
Seems that is not enough for you?  If no, I have no objections to make
a stub  for arm32.

Well, the only bits arm64 specifics in this file are the access to the
system registers. So renaming to time_arm64.c seems a bit overkill...

If there are plan to make arm32 a correct port on Unikraft, then
splitting the code would be the best. If there are no plan to get arm32,
then maybe you should think of killing it completely.

Arm32 xen plat is initially supported but no one  has touched that for a long
time. Currently let’s focus on arm64 kvm plat only. If the requirements changes,
we can support arm32 additionally. What do you think about it?

I am not asking to implement arm32, I am only suggesting to try to split the code rather than trying to mix common code vs arch specific code in plat/common/arm. That directory in particular is looking messier and messier as new series are posted.

Cheers,

--
Julien Grall

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