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Re: [RFC PATCH 2/2] plat/rcar: Add region id support for PCI
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>
- Date: Tue, 21 Apr 2026 08:45:42 +0000
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Tue, 21 Apr 2026 08:45:55 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [RFC PATCH 2/2] plat/rcar: Add region id support for PCI
On 4/21/26 11:28, Jan Beulich wrote:
> On 21.04.2026 09:57, Mykyta Poturai wrote:
>> With Region ID enabled, all CPU memory accesses need to have rgid bits
>> set in the physical address. This creates a problem for PCI BAR
>> accesses, as it would require all BARs to be 64bit.
>
> I don't understand this. CPU accesses of addresses read / derived from
> BARs can be massaged in any way the OS likes. That doesn't require the
> BARs to be 64-bit. Are you trying to arrange for RGID to be transparent
> to guests?
>
> Jan
Yes, making it transparent to guests is the goal.
--
Mykyta
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