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From: gengdongjiu <gengdongjiu@huawei.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm <qemu-arm@nongnu.org>, QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [RESEND PATCH] target/arm: change arch timer registers access permission
Date: Mon, 11 Mar 2019 15:55:33 +0000	[thread overview]
Message-ID: <C87848E9-4108-4586-B433-BF026017D406> (raw)
In-Reply-To: <CAFEAcA9yr3trFz7ZFsS-P-g=gxe=MX6Eet_dTdcOCSdhW7_J4w@mail.gmail.com>

understand now，thanks for the explaination, I will update it.
发件人：Peter Maydell <peter.maydell@linaro.org>
收件人：gengdongjiu <gengdongjiu@huawei.com>
抄 送：qemu-arm <qemu-arm@nongnu.org>;QEMU Developers <qemu-devel@nongnu.org>
时间：2019-03-11 23:39:32
主 题：Re: [RESEND PATCH] target/arm: change arch timer registers access permission

On Mon, 11 Mar 2019 at 15:24, gengdongjiu <gengdongjiu@huawei.com> wrote:
> So If QEMU defined the timer registers read only in PL0, even though it has been configured to have write permission in PL0 by high PLx, we still cannot have
> Write permission, because QEMU will firstly check the defined permission and then check the configured permission by high PLx.

I'm afraid I don't understand what you're trying to say here.

Yes, it was a bug that we marked these registers as read-only for PL0,
and we should fix it.

What I am trying to say is that
 .access = PL1_RW | PL0_RW

is exactly equivalent to
 .access = PL0_RW

and we should use the simpler version of the expression.

(If you look at the definitions of all the PL*_ constants,
you can see that PL0_W implies PL1_W:
#define PL0_W (0x01 | PL1_W)
and similarly for PL0_R. So all the bits in the bitfield that would be
set by PL1_RW are also set by PL0_RW.)

thanks
-- PMM

  reply	other threads:[~2019-03-11 15:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-11 15:24 [Qemu-devel] [RESEND PATCH] target/arm: change arch timer registers access permission gengdongjiu
2019-03-11 15:39 ` Peter Maydell
2019-03-11 15:55   ` gengdongjiu [this message]
  -- strict thread matches above, loose matches on Subject: below --
2019-03-11 14:49 gengdongjiu
2019-03-11  8:29 gengdongjiu
2019-03-11 14:09 ` Peter Maydell

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