VirtualBox

Ticket #8739 (closed defect: fixed)

Opened 3 years ago

Last modified 3 years ago

Checksum error in BIOS function int 13h, ah=48h (extended get drive parameters) => Fixed in SVN

Reported by: madanra Owned by:
Priority: minor Component: virtual disk
Version: VirtualBox 4.0.4 Keywords: bios drive parameters checksum
Cc: Guest type: other
Host type: other

Description

I've started writing an OS, and noticed that the BIOS function 13h, ah=48h (extended get drive parameters, see  http://www.ctyme.com/intr/rb-0715.htm for Ralf Brown's description) appears to give an incorrect checksum. In the description of the function, Ralf Brown says "checksum of bytes 1Eh-40h (two's complement of sum, which makes the 8-bit sum of bytes 1Eh-41h equal 00h)". On Bochs and VirtualPC, this is the case, but on VirtualBox the byte sum is FFh.

Change History

comment:1 Changed 3 years ago by madanra

Ah, should have looked in the source. Line 5936 of /trunk/src/VBox/Devices/PC/BIOS/rombios.c has:
checksum = ~checksum;
when I believe, from the description in Ralf Brown, it should be:
checksum = -checksum;

comment:2 Changed 3 years ago by frank

  • Summary changed from Checksum error in BIOS function int 13h, ah=48h (extended get drive parameters) to Checksum error in BIOS function int 13h, ah=48h (extended get drive parameters) => Fixed in SVN

Thanks for the feedback. This bug will be fixed in the next major release.

comment:3 Changed 3 years ago by frank

  • Status changed from new to closed
  • Resolution set to fixed

Fixed in 4.1.0.

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