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From: Kevin Wolf <kwolf@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org,
	"Peter Maydell" <peter.maydell@linaro.org>,
	qemu-arm@nongnu.org, "Hanna Reitz" <hreitz@redhat.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"John Snow" <jsnow@redhat.com>,
	"Kashyap Chamarthy" <kchamart@redhat.com>,
	"Xiang Zheng" <zhengxiang9@huawei.com>
Subject: Re: [PATCH v2] pflash: Only read non-zero parts of backend image
Date: Tue, 10 Jan 2023 15:08:04 +0100	[thread overview]
Message-ID: <Y71xRO+sHh+TZ3PS@redhat.com> (raw)
In-Reply-To: <20221220084246.1984871-1-kraxel@redhat.com>

Am 20.12.2022 um 09:42 hat Gerd Hoffmann geschrieben:
> From: Xiang Zheng <zhengxiang9@huawei.com>
> 
> Currently we fill the VIRT_FLASH memory space with two 64MB NOR images
> when using persistent UEFI variables on virt board. Actually we only use
> a very small(non-zero) part of the memory while the rest significant
> large(zero) part of memory is wasted.
> 
> So this patch checks the block status and only writes the non-zero part
> into memory. This requires pflash devices to use sparse files for
> backends.
> 
> Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
> 
> [ kraxel: rebased to latest master ]
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Thanks, applied to the block branch.

Even though discussion is ongoing about using alternative devices, it
seems to me that this is a simple optimisation that doesn't change the
behaviour as seen by the guest and that we want to have either way. If
anyone objects and wants me to drop the patch again, let me know.

Kevin



      parent reply	other threads:[~2023-01-10 15:12 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-20  8:42 [PATCH v2] pflash: Only read non-zero parts of backend image Gerd Hoffmann
2022-12-20  9:08 ` Daniel P. Berrangé
2022-12-20  9:30 ` Philippe Mathieu-Daudé
2022-12-20 15:33   ` Gerd Hoffmann
2022-12-23 14:33     ` Ard Biesheuvel
2023-01-02 11:11       ` Gerd Hoffmann
2023-01-10 14:08 ` Kevin Wolf [this message]

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