Thanks. I will try writeback=off as well
The manual says "The default mode is *cache=writeback*." and further on
it says-
By default, the cache.writeback=on mode is used. It will report data
writes as completed as soon as the data is present in the host page
cache. This is safe as long as your guest OS makes sure to correctly
flush disk caches where needed. If your guest OS does not handle
volatile disk write caches correctly and your host crashes or loses
power, then the guest may experience data corruption.
For such guests, you should consider using cache.writeback=off. This
means that the host page cache will be used to read and write data,
but write notification will be sent to the guest only after QEMU has
made sure to flush each write to the disk. Be aware that this has a
major impact on performance.
On 2024/03/14 08:25, Louis Santillan wrote:
You might try updating the 2nd drive's argument to `-drive
file=fat:rw:dosfiles/,format=raw,cache=writeback`. [0]
[0]
https://manpages.debian.org/unstable/qemu-system-x86/qemu-system-i386.1.en.html
On Wed, Mar 13, 2024 at 10:29 AM h...@iafrica.com <h...@iafrica.com> wrote:
I removed CDROM and Sound support. I moved all program directories
from the D: drive (FAT16 access drive) to the C: drive and this
appears to have improved the speed to about 7x slower. I then
checked to see if KVM was running and it was.
The command line I was using to invoke the emulator was:-
$ qemu-system-i386 -m 32 -rtc base=localtime -drive
file=dos.img,index=0,media=disk,format=raw -drive
file=fat:rw:dosfiles/,format=raw -boot order=c -display sdl
I then added "-enable-kvm"
eg.
$ qemu-system-i386 -m 32 -rtc base=localtime -drive
file=dos.img,index=0,media=disk,format=raw -drive
file=fat:rw:dosfiles/,format=raw -boot order=c -display sdl
-enable-kvm
This has moved speed to parity to 2x slower which is excellent.
I have switched to the 4DOS shell with no speed penalty. In 4DOS I
have always used Function key F11 to toggle between two
directories. This does not work as QEMU appears to use F11 to
toggle between current window size and full screen. I have
searched on the Internet but not found any reference to the use
off F11 in QEMU. Anyone have any ideas how to reassign the key? I
suspect it is hard coded?
Using drive D:, the access drive, appears to be problematic. Best
not to use it other than transfer files.
On 2024/03/13 18:53, Louis Santillan wrote:
What was the qemu command you used? It sounds like you paying a
double penalty somewhere for how you’re get the disk image into
qemu. Loopback devices pay some penalty. 10x seems like some
option is missing to improve performance.
On Wed, Mar 13, 2024 at 2:57 AM hms--- via Freedos-user
<freedos-user@lists.sourceforge.net> wrote:
Hi All
Some feedback. Creating a 2G image allowed me to assemble
source code
correctly. The only penalty being speed. About 6 to 11 times
slower than
running DOS under XP.
I mounted the image and copied source files from backup
directory to
mounted C: drive.
Lubuntu Linux error on boot up resolved. QEMU-KVM had crashed
on two
occasions and logs created in the /dev/crash directory.
Deleting the log
files in /dev/crash removed the error message on start up.
I used "mount" instead of "guestmount". Steps below.
Display start sector and sector size:
$ fdisk -l dos.img
Eg. 63 and 512 bytes. Offset = 63 * 512 = 32256
Create directory:
$ mkdir /tmp/dos
Mount image in directory:
$ sudo mount -o loop,offset=32256 dos.img /tmp/dos
Copy directories:
Eg.
$ cp -r /temp/source-dir /tmp/dos
Unmount image:
umount /tmp/dos
John
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