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.
next prev parent 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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