From: Jeff Garzik <jgarzik@pobox.com>
To: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Jens Axboe <axboe@suse.de>, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Worrisome IDE PIO transfers...
Date: Sat, 28 Feb 2004 18:24:28 -0500 [thread overview]
Message-ID: <4041232C.7030305@pobox.com> (raw)
Looking at the function that is used to transfer data when in PIO mode...
void taskfile_output_data (ide_drive_t *drive, void *buffer, u32 wcount)
{
if (drive->bswap) {
ata_bswap_data(buffer, wcount);
HWIF(drive)->ata_output_data(drive, buffer, wcount);
ata_bswap_data(buffer, wcount);
} else {
HWIF(drive)->ata_output_data(drive, buffer, wcount);
}
}
Swapping the data in-place is very, very wrong... you don't want to be
touching the data that userspace might have mmap'd ... Additionally,
byteswapping back and forth for each PIO sector chews unnecessary CPU.
Seems to me the architecture's OUTS[WL] hook (or a new, similar hook)
that swaps as it writes would be _much_ preferred, and eliminate this
possible data corruption issue.
Jeff
next reply other threads:[~2004-02-28 23:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-28 23:24 Jeff Garzik [this message]
2004-02-29 0:21 ` Worrisome IDE PIO transfers Bartlomiej Zolnierkiewicz
2004-02-29 0:58 ` Jeff Garzik
2004-02-29 3:05 ` Bartlomiej Zolnierkiewicz
2004-02-29 8:52 ` Geert Uytterhoeven
2004-02-29 19:23 ` Richard Zidlicky
2004-02-29 20:36 ` Bartlomiej Zolnierkiewicz
2004-03-01 10:43 ` Richard Zidlicky
2004-02-29 1:50 ` Matt Mackall
2004-02-29 2:41 ` Jeff Garzik
2004-02-29 3:08 ` Bartlomiej Zolnierkiewicz
2004-02-29 9:32 ` Aubin LaBrosse
2004-03-01 0:47 ` Bartlomiej Zolnierkiewicz
2004-03-01 13:23 ` Christophe Saout
2004-03-01 16:45 ` Bartlomiej Zolnierkiewicz
2004-02-29 8:50 ` Geert Uytterhoeven
2004-02-29 14:55 ` Bartlomiej Zolnierkiewicz
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