A bug about cache inconsistency report - Hans Hu(SH-RD)

From: "Hans Hu(SH-RD)" <HansHu@zhaoxin.com>
To: "'alsa-devel@alsa-project.org'" <alsa-devel@alsa-project.org>
Subject: A bug about cache inconsistency report
Date: Tue, 31 Jul 2018 10:52:04 +0000	[thread overview]
Message-ID: <c859756ba7f742869642fd80a105c3c8@zhaoxin.com> (raw)

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Hi All,

               Try send an email.

               Appearance:
when use non-snoop + ioctl path combination, an issue occurs:
usage: aplay -D plughw:0,0 44100_S16_LE_2c.wav
Ubuntu, it performance intermittently noise;

Root case:
               Function set_pages_array_wc marked the PTE of the original address; Function set_memory_wc marked the PTE both original and after vmaped address.
[cid:image002.png@01D428FF.92621520]
However, cache or not in transmission process is based on the PTE of the later, and the set_pages_array_wc did't mark it, so a cache inconsistency issue occurs.

               Related bug:
               SHA1 ID: 9ddf1aeb2134e72275c97a2c6ff2e3eb04f2f27a

Best Regards!
Hans Hu

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