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From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien.grall@arm.com>
Cc: Hunyue Yau <hy-gsoc@hy-research.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Andrii Anisov <Andrii_Anisov@epam.com>,
	Oleksandr Tyshchenko <Oleksandr_Tyshchenko@epam.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Denis Obrezkov <denisobrezkov@gmail.com>,
	Iain Hunter <drhunter95@gmail.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] Starting to port xen on beagleboard-x15 (GSoC 2019 project)
Date: Tue, 18 Jun 2019 09:49:28 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.1906180949060.2072@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <07a7084a-b798-0cc7-cca4-3fe58ea95835@arm.com>

On Tue, 18 Jun 2019, Julien Grall wrote:
> On 18/06/2019 13:28, Andrii Anisov wrote:
> > +xen-devel
> 
> Please don't cross-post e-mail. If you move the thread to xen-devel, then
> xen-users should be droppped.
> 
> > 
> > Hello Julien,
> > 
> > > I am a bit confused. Linux is able to bring-up CPU in hyp mode with the
> > > current
> > > U-boot. Why would we need more changes for Xen?
> > 
> > TI's ROM code starts all CPUs in NS PL1, doesn't matter if it is boot or
> > secondary core.
> > If you look at Linux code [1], you'll see, that after the secondary core
> > bringup Linux does switch that core from NS PL1 to PL2 (hyp mode) using ROM
> > code interface (smc 0).
> > At some moment XEN dropped all to-hyp-mode switching code. So I did switch
> > secondaries to hyp mode in u-boot with the loop which replicates the ROM
> > Code logic in terms of waiting for an event and checking aux registers.
> 
> Switch to hyp-mode is fairly complex and depends on your processor. Hence why
> it was dropped in both Linux and Xen.
> 
> However, calling an SMC would be acceptable to me. Stefano, any opinion?

Yes, it would be trivial to maintain something like that.

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      parent reply	other threads:[~2019-06-18 16:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <287117b9-952c-1a92-26e0-9597df936c27@gmail.com>
     [not found] ` <cd936ab7-df65-1615-a03a-bea30b5814f9@arm.com>
     [not found]   ` <f3596bd5-ede3-7299-e28f-033ad32e6c99@gmail.com>
     [not found]     ` <62194faf-0bf8-61b8-a69f-e41934fb5a43@arm.com>
     [not found]       ` <0c900a15-14ab-9947-bffe-2fbeed176486@gmail.com>
     [not found]         ` <CALC81-vaVKgZoi27MauGTxjda8mchy5GRLipu5z=v1vh9fyvAg@mail.gmail.com>
     [not found]           ` <747dd124-3511-f010-dac7-b9b23d7b44ad@gmail.com>
     [not found]             ` <CALC81-tewzAtaaH94U1nVc-UiacR_YvqhaYcPXtXcviTFHAG8A@mail.gmail.com>
     [not found]               ` <ecb2cf41-51e5-2ff2-5e61-72be64399e40@arm.com>
     [not found]                 ` <AM6PR0302MB32215CD7FAED139C682D92A386EA0@AM6PR0302MB3221.eurprd03.prod.outlook.com>
     [not found]                   ` <ef82a028-9e4e-9976-d205-42cbc4bfc8ac@arm.com>
     [not found]                     ` <AM6PR0302MB3221D649900B54C2FFA7003A86EA0@AM6PR0302MB3221.eurprd03.prod.outlook.com>
2019-06-18 12:28                       ` [Xen-devel] Starting to port xen on beagleboard-x15 (GSoC 2019 project) Andrii Anisov
2019-06-18 12:54                         ` Julien Grall
2019-06-18 13:27                           ` Andrii Anisov
2019-06-18 13:47                             ` Andrii Anisov
2019-06-18 16:19                             ` Julien Grall
2019-06-19 12:01                               ` Andrii Anisov
2019-06-19 14:33                                 ` Denis Obrezkov
2019-06-19 15:06                                   ` Julien Grall
2019-06-19 15:27                                     ` Andrii Anisov
2019-06-19 15:32                                       ` Julien Grall
2019-06-19 16:10                                         ` Andrii Anisov
2019-06-19 16:31                                           ` Julien Grall
2019-06-19 21:51                                         ` Denis Obrezkov
2019-06-19 22:08                                           ` Julien Grall
2019-06-19 22:06                                     ` Denis Obrezkov
2019-06-19 22:16                                       ` Julien Grall
2019-06-18 16:49                           ` Stefano Stabellini [this message]

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