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From: Thomas Huth <thuth@redhat.com>
To: Michael Tokarev <mjt@tls.msk.ru>,
	QEMU Development <qemu-devel@nongnu.org>,
	David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-ppc@nongnu.org, "Cédric Le Goater" <clg@kaod.org>,
	"Greg Kurz" <groug@kaod.org>
Subject: Re: ppc kvm: support of 64K guest page size with 4K host pagesize?
Date: Thu, 5 Jun 2025 08:52:44 +0200	[thread overview]
Message-ID: <58abce8b-c5c2-4fd1-a32c-2d887445097d@redhat.com> (raw)
In-Reply-To: <0392df3f-c9fc-4372-a131-f0a7c3313c9c@tls.msk.ru>

On 05/06/2025 08.34, Michael Tokarev wrote:
> There's a bug report filed in debian against qemu,
> https://bugs.debian.org/1107288 - saying kvm on ppc does not
> work on debian (anymore) due to qemu requesting unrealistic
> (non-existing) page size of 64K on a host which only has 4K.
> 
> I don't know much about PPC, - what's the issue here? Should
> qemu use the same page size for kvm as on the host?

Looking at

  https://gitlab.com/qemu-project/qemu/-/commit/2309832afdaf8d6451ebc2e81bace8eb8ea41293

it seems like this was done on purpose? David, do you remember why 
auto-detecting was not a good idea here?

Anyway, seems like there is a hpt-max-page-size property that could be used 
to set the value manually - maybe you could suggest that to the user as a 
work-around?

  Thomas



  reply	other threads:[~2025-06-05  6:53 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-05  6:34 ppc kvm: support of 64K guest page size with 4K host pagesize? Michael Tokarev
2025-06-05  6:52 ` Thomas Huth [this message]
2025-06-05 10:25   ` David Gibson

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