On 04/07/16 21:36, Laszlo Ersek wrote:
> On 04/07/16 20:24, Jordan Justen wrote:
>> Someone was reporting slowness with the Windows 7 ISO on irc a few
>> days back. Maybe this is the cause?
> I think you are referring to the following discussion on April 4th:
>> <Naruni> if i use a VM in bios mode it operates at full performance
> The domain XML clarifies another thing: the CD-ROM is IDE, not
> virtio-scsi. Also, there is no other disk drive (of any kind).
Sigh, this doesn't look good. If you look at the SeaBIOS source, it has
ata_pio_transfer() in "src/hw/ata.c", doing:
for (;;) {
if (iswrite) {
// Write data to controller
dprintf(16, "Write sector id=%p dest=%p\n", op->drive_gf, buf_fl);
if (CONFIG_ATA_PIO32)
outsl_fl(iobase1, buf_fl, blocksize / 4);
else
outsw_fl(iobase1, buf_fl, blocksize / 2);
} else {
// Read data from controller
dprintf(16, "Read sector id=%p dest=%p\n", op->drive_gf, buf_fl);
if (CONFIG_ATA_PIO32)
insl_fl(iobase1, buf_fl, blocksize / 4);
else
insw_fl(iobase1, buf_fl, blocksize / 2);
}
buf_fl += blocksize;
The outsl_fl / outsw_fl / insl_fl / insw_fl functions are forwarded by
"src/farptr.h" to primitives in "src/x86.h" (without the _fl suffix). Those
primitives *do* use inline assembly with the REP prefix.
... Right, I can reproduce the issue. Booting a Fedora LiveCD from an IDE
CD-ROM takes ages, and the host CPU is pegged, in system load. :( :( :(
Let me see if I can come up with a patch for this. Good catch, Jordan!
Laszlo
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