From: Michael Ellerman <mpe@ellerman.id.au>
To: benh@au1.ibm.com, Michael Neuling <mikey@neuling.org>,
Oliver O'Halloran <oohall@gmail.com>,
linuxppc-dev@lists.ozlabs.org
Cc: Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH 2/2] KVM: PPC: hypervisor large decrementer support
Date: Tue, 07 Jun 2016 23:04:13 +1000 [thread overview]
Message-ID: <1465304653.30446.5.camel@ellerman.id.au> (raw)
In-Reply-To: <1464903967.3078.316.camel@au1.ibm.com>
On Fri, 2016-06-03 at 07:46 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2016-06-01 at 16:23 +1000, Michael Neuling wrote:
> > FWIW you can use:
> > andis. reg,reg,(LPCR_LD)@ha
>
> @h in that case. Probably the same result but technically @ha is for
> arithmetic operations.
In this case it doesn't matter, because LPCR_LD is a single bit constant.
But if bit 15 of your constant happens to be 1, using @ha will mean 1 is added
to the high 16 bits of the value.
eg. if you have:
#define CONSTANT 0x00208000
lis r4,CONSTANT@ha
You get:
10000118: 21 00 80 3c lis r4,33
^
= 0x21
Documented (sort of) here:
http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#RELOC-TYPE
#ha(value) denotes the high adjusted value: bits 16 through 31 of the indicated value, compensating for #lo() being treated as a signed number:
#ha(x) = (((x >> 16) + ((x & 0x8000) ? 1 : 0)) & 0xffff)
cheers
next prev parent reply other threads:[~2016-06-07 13:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-10 4:57 [PATCH v3 1/2] powerpc/timer - large decrementer support Oliver O'Halloran
2016-05-10 4:57 ` [PATCH v3 2/2] KVM: PPC: hypervisor " Oliver O'Halloran
2016-05-11 5:05 ` [PATCH v3 1/2] powerpc/timer - " Balbir Singh
2016-05-31 6:25 ` Michael Neuling
2016-05-31 7:05 ` oliver
2016-05-31 7:16 ` [PATCH " Oliver O'Halloran
2016-05-31 7:16 ` [PATCH 2/2] KVM: PPC: hypervisor " Oliver O'Halloran
2016-06-01 6:23 ` Michael Neuling
2016-06-02 21:46 ` Benjamin Herrenschmidt
2016-06-07 13:04 ` Michael Ellerman [this message]
2016-06-22 7:30 ` oliver
2016-06-01 5:28 ` [PATCH 1/2] powerpc/timer - " Michael Neuling
2016-06-03 2:01 ` Balbir Singh
-- strict thread matches above, loose matches on Subject: below --
2016-04-12 4:38 Oliver O'Halloran
2016-04-12 4:38 ` [PATCH 2/2] KVM: PPC: hypervisor " Oliver O'Halloran
2016-04-12 4:53 ` kbuild test robot
2016-04-12 7:35 ` Balbir Singh
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