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Re: [PATCH v4 07/17] target/ppc: Disconnect hflags from MSR
From: |
David Gibson |
Subject: |
Re: [PATCH v4 07/17] target/ppc: Disconnect hflags from MSR |
Date: |
Wed, 24 Mar 2021 12:42:07 +1100 |
On Tue, Mar 23, 2021 at 11:04:03AM -0600, Richard Henderson wrote:
> On 3/22/21 5:54 PM, David Gibson wrote:
> > On Mon, Mar 22, 2021 at 10:55:46AM -0600, Richard Henderson wrote:
> > > On 3/21/21 9:52 PM, David Gibson wrote:
> > > > > +/*
> > > > > + * Bits for env->hflags.
> > > > > + *
> > > > > + * Most of these bits overlap with corresponding bits in MSR,
> > > > > + * but some come from other sources. Be cautious when modifying.
> > > >
> > > > Yeah.. I'm not sure "be cautious" is enough of a warning. The exact
> > > > value of some but not all of these flags must equal that for the
> > > > corresponding MSR bits, which is terrifyingly subtle.
> > >
> > > Fair. How about, for the comment here, "This is validated in
> > > hreg_compute_hflags."
> > >
> > > > > + /* Some bits come straight across from MSR. */
> > > > > + msr_mask = ((1 << MSR_LE) | (1 << MSR_PR) |
> > > > > + (1 << MSR_DR) | (1 << MSR_IR) |
> > > > > + (1 << MSR_FP) | (1 << MSR_SA) | (1 << MSR_AP));
> > >
> > > Here, and in every other spot within this function where we manipulate
> > > msr_mask,
> > >
> > > QEMU_BUILD_BUG_ON(MSR_LE != HFLAGS_LE);
> >
> > Seems reasonable.
>
> Hah. Your paranoia was well-founded. Typo in HFLAGS_PR. :-)
Heh :).
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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- [PATCH v4 01/17] target/ppc: Move helper_regs.h functions out-of-line, (continued)
[PATCH v4 10/17] target/ppc: Create helper_scv, Richard Henderson, 2021/03/15
[PATCH v4 13/17] target/ppc: Remove env->immu_idx and env->dmmu_idx, Richard Henderson, 2021/03/15
[PATCH v4 14/17] hw/ppc/pnv_core: Update hflags after setting msr, Richard Henderson, 2021/03/15