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From: Fabiano Rosas <farosas@linux.ibm.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	"Maxiwell S. Garcia" <maxiwell@linux.ibm.com>
Subject: Re: [PATCH] target/ppc: fix memory dump endianness in QEMU monitor
Date: Tue, 24 Dec 2019 13:10:34 -0300	[thread overview]
Message-ID: <8736d9g0w5.fsf@linux.ibm.com> (raw)
In-Reply-To: <20191224051904.GK38380@umbus.modem>

David Gibson <david@gibson.dropbear.id.au> writes:

>> It looks like the hflags MSR_LE is being updated correctly with TCG. But
>> with KVM we only touch it on system_reset
>
> Ah.. right.  I think to fix that we'd want an hreg_compute_hflags() at
> the end of sucking the state out of KVM.
>

Hm.. The hflags is a TCG thing that does not get used with KVM at all,
except for that one bit in the monitor disas function. I'd rather keep
it completely out of kvm_enabled code.

Couldn't we perhaps make it conditional on the acceleration type?
Using kvm_enabled() or some ifdef.

Thanks

>> (and possibly h_cede? I don't
>> know if it is QEMU who handles it).
>
> It's KVM.  If we used the qemu one it would add an awful lot of
> latency to cedes.
>> 
>> So I would let hflags be.
>> 
>> 
>> ... Actually, I don't really know the purpose of hflags. It comes from:
>> 
>>   commit 3f3373166227b13e762e20d2fb51eadfa6a2d653
>>   Author: Fabrice Bellard <fabrice@bellard.org>
>>   Date:   Wed Aug 20 23:02:09 2003 +0000
>>   
>>       pop ss, mov ss, x and sti disable irqs for the next instruction -
>>       began dispatch optimization by adding new x86 cpu 'hidden' flags
>>       
>>       
>>       git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@372 c046a42c-6fe2-441c-8c8c-71466251a162
>> 
>> Could any one clarify that?
>
> Not really.  It's really, really old, in the cruft bits of TCG I don't
> much understand.


  reply	other threads:[~2019-12-24 16:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-19 16:38 [PATCH] target/ppc: fix memory dump endianness in QEMU monitor Maxiwell S. Garcia
2019-12-23  6:30 ` David Gibson
2019-12-23 21:35   ` Maxiwell S. Garcia
2019-12-24  5:10     ` David Gibson
2019-12-23 23:27   ` Fabiano Rosas
2019-12-24  5:19     ` David Gibson
2019-12-24 16:10       ` Fabiano Rosas [this message]
2019-12-26  1:54         ` David Gibson

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