[ros-kernel] Freeldr bug

[Mike L. <Mi...@ml...>]

Following some recent changes to bochs/bios a problem was noticed whereby
freeldr stopped working.

This was traced by the efforts of Christophe Bothamy to an error in
freeldr/arch/i386/biosdisk.S

the code currently reads

EXTERN(_BiosInt13ReadExtended)
    .code32

    pushal

    /* Get parameters */
    movl    0x24(%esp),%eax
    movl    %eax,_int13_extended_drive
    movl    0x28(%esp),%eax
    movl    %eax,_packet_lba_sector_number
    movl    0x2c(%esp),%eax
    movw    %ax,_packet_sector_count
    movl    %eax,_int13_extended_sector_count
    movl    0x30(%esp),%eax                         // Get buffer address in
eax
    shrl    $4,%eax                                 // Make linear address
into segment
    movw    %ax,_packet_transfer_buffer_segment     // Save segment
    movl    0x34(%esp),%eax                         // Get buffer address in
eax
    andl    $0x0f,%eax                              // Make linear address
into offset
    movw    %ax,_packet_transfer_buffer_offset      // Save offset

The 34 in the third line from the end needs to be 30.

I have confirmed that with this change freeldr can again be booted from a
hard disk with the current CVS version of bochs.

regards

Mike Lerwill