From: Alex Bligh <alex@alex.org.uk>
To: Saptarshi Sen <saptarshi.mrg@gmail.com>,
qemu-devel@nongnu.org, qemu-discuss@nongnu.org
Cc: Alex Bligh <alex@alex.org.uk>
Subject: Re: [Qemu-devel] IO : Disk Sector Reads not aligned
Date: Tue, 09 Jul 2013 19:06:02 +0100 [thread overview]
Message-ID: <64716B136F12C649DA0F0C40@nimrod.local> (raw)
In-Reply-To: <CAG5Np+pCepDQb7fiwBa_OjoSwQWgOnBDD9NWThq34i8h2UJPHA@mail.gmail.com>
--On 10 July 2013 01:04:35 +0800 Saptarshi Sen <saptarshi.mrg@gmail.com>
wrote:
> the sector reads are not 512 bytes aligned.
>
> I am gathering the stats from hw/ide/core.c in the function
>
> ide_dma_cb. variable :sector_num
>
> Should not these disk reads be 512 bytes aligned.
As illustrated by the code below, sector_num is the number of the sector.
The byte offset is sector_num << 9. As sector_num is an integer, this makes
all the reads 512 byte aligned as far as I can see.
n = s->io_buffer_size >> 9;
sector_num = ide_get_sector(s);
if (n > 0) {
dma_buf_commit(s);
sector_num += n;
ide_set_sector(s, sector_num);
s->nsector -= n;
}
--
Alex Bligh
prev parent reply other threads:[~2013-07-09 18:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-09 17:04 [Qemu-devel] IO : Disk Sector Reads not aligned Saptarshi Sen
2013-07-09 18:06 ` Alex Bligh [this message]
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