diff options
Diffstat (limited to 'src/VBox/Devices/PC/BIOS/notes.txt')
| -rw-r--r-- | src/VBox/Devices/PC/BIOS/notes.txt | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/VBox/Devices/PC/BIOS/notes.txt b/src/VBox/Devices/PC/BIOS/notes.txt index 07017cb9..423ea134 100644 --- a/src/VBox/Devices/PC/BIOS/notes.txt +++ b/src/VBox/Devices/PC/BIOS/notes.txt @@ -8,6 +8,9 @@ - OS/2 (WSeB/MCP/ACP) and Windows 98 SE are some of the very few operating systems which use the El Torito floppy emulation. +- NetWare 5.1 is one of the *extremely* few users of El Torito hard disk + emulation. + - Keystroke check (INT 16h, fn 01h/10h) always enables interrupts on return. DOS POWER.EXE depends on that in some situations. @@ -26,6 +29,9 @@ - OS/2 is the only known guest which can run the 16-bit PCI BIOS in protected mode (but only if the 32-bit PCI BIOS is unavailable). +- NetWare 6.x is the only known guest which uses the PCI BIOS service to read + the IRQ routing table. + - Any disk reads which use bus-master DMA (AHCI, IDE BM) must use VDS (Virtual DMA Services) when present. Otherwise any reads/writes when the real mode addresses don't map directly to physical addresses will fail @@ -40,6 +46,11 @@ and clear the memory. For those, the FDPT must be in the BIOS ROM area, or the OS will destroy it (even when it's at 0:300 in the IVT). +- Windows NT (including XP) uses INT 13h/08h to obtain the DPT for each floppy + drive. NT assumes a 13-byte DPT which includes the number of tracks. NT will + refuse to read more tracks than the DPT specifies and formats as many tracks + as the DPT specifies. + - Windows 98 SE boot CD uses 32-bit registers in real mode and will fail in mysterious ways if BIOS trashes high bits of EAX (and likely others). @@ -52,6 +63,22 @@ - Windows 98 is one of the few APM 1.2 users; Windows 95 uses APM 1.1, while newer systems prefer ACPI. +- QNX4 calls 16-bit protected-mode PCI BIOS in an environment where ESP is + 16-bit but SS is a 32-bit stack segment. In such environments, using the + ENTER/LEAVE sequence is fatal if the high word of EBP is non-zero (which + it will be with QNX 4.25). LEAVE propagates the high word of EBP into ESP + with fatal consequences. + +- Plan 9 also runs 16-bit code with a 32-bit stack segment, except Plan 9 + thinks it counts as real mode. Same ENTER/LEAVE problem as above. + +- AIX 1.3 is a rare user of INT 15h/89h (switch to protected mode) service. + +- IBM OS/2 1.0/1.1 (but not other versions!) attempt to execute a 286 LOADALL + instruction. LOADALL must be emulated for OS/2 to work properly. HIMEM.SYS + version 2.03 and later also contains 286 LOADALL code but this will not be + executed on 386+ processors. + Notes on BIOS implementation ---------------------------- @@ -91,6 +118,9 @@ protected-mode APM is written in assembler for both 16-bit and 32-bit calls, with a small 32->16 thunk. +- The -of switch can be used to avoid generating ENTER/LEAVE instructions. + This appears to be an undocumented and perhaps unintentional side effect. + Code size notes (code as of 7/6/2011): |