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* Check for disk extensions before using them (mostly for good practice reasons)

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* A CHS read error would previously be hidden by a successful disk system reset.
  Not that it matters much because it'd have resulted in a non-booting system
  anyway.
* Add some more debug output, minor cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30643 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2009-05-06 11:55:19 +00:00
parent 2a8d619c9e
commit 03a574d8cd
1 changed files with 30 additions and 5 deletions

35
src/system/boot/platform/bios_ia32/devices.cpp

@ -198,6 +198,22 @@ check_cd_boot(BIOSDrive *drive)
}
static bool
are_extensions_available(uint8 drive)
{
struct bios_regs regs;
regs.eax = BIOS_IS_EXT_PRESENT;
regs.ebx = 0x55aa;
regs.edx = drive;
call_bios(0x13, &regs);
TRACE(("checking extensions: carry: %u; ebx: 0x%08lx; ecx: 0x%08lx\n",
regs.flags & CARRY_FLAG, regs.ebx, regs.ecx));
return (regs.flags & CARRY_FLAG) == 0 && regs.ebx == 0xaa55
&& (regs.ecx & 0x01 /* supports device access using packet */) != 0;
}
static status_t
get_ext_drive_parameters(uint8 drive, drive_parameters *targetParameters)
{
@ -528,7 +544,7 @@ BIOSDrive::BIOSDrive(uint8 driveID)
{
TRACE(("drive ID %u\n", driveID));
if (driveID < 0x80
if (driveID < 0x80 || !are_extensions_available(driveID)
|| get_ext_drive_parameters(driveID, &fParameters) != B_OK) {
// old style CHS support
@ -627,12 +643,16 @@ BIOSDrive::ReadAt(void *cookie, off_t pos, void *buffer, size_t bufferSize)
uint32 cylinder = head / fParameters.heads;
head %= fParameters.heads;
if (cylinder >= fParameters.cylinders)
if (cylinder >= fParameters.cylinders) {
TRACE(("cylinder value %lu bigger than available %lu\n",
cylinder, fParameters.cylinders));
return B_BAD_VALUE;
}
// try to read from the device more than once, just to make sure it'll work
struct bios_regs regs;
int32 tries = 3;
bool readWorked = false;
while (tries-- > 0) {
regs.eax = BIOS_READ | blocksRead;
@ -642,21 +662,26 @@ BIOSDrive::ReadAt(void *cookie, off_t pos, void *buffer, size_t bufferSize)
regs.ebx = kExtraSegmentScratch;
call_bios(0x13, &regs);
if ((regs.flags & CARRY_FLAG) == 0)
if ((regs.flags & CARRY_FLAG) == 0) {
readWorked = true;
break;
}
TRACE(("read failed\n"));
if (tries < 2) {
// reset disk system
TRACE(("reset disk system\n"));
regs.eax = BIOS_RESET_DISK_SYSTEM;
regs.edx = fDriveID;
call_bios(0x13, &regs);
}
// wait a bit between the retries (1/20 sec)
spin(50000);
}
if (regs.flags & CARRY_FLAG) {
if (!readWorked) {
dprintf("reading %ld bytes from drive %u failed at %Ld\n",
blocksRead, fDriveID, pos);
return B_ERROR;