Kernel & BIOS return differing head/sector geometries
hello
I'm getting this while running lilo from kernel 2.5.72mm2. What does it means?
Could it be dangerous?
Thanks.
bash-2.05b# lilo
Warning: Kernel & BIOS return differing head/sector geometries for device 0x80
Kernel: 13424 cylinders, 15 heads, 63 sectors
BIOS: 788 cylinders, 255 heads, 63 sectorsAdded 2572mm2
Added 2573desktop
Added 2421-ck1 *
Quoted 5 lines · Luis Miguel Garcia
I'm getting this while running lilo from kernel 2.5.72mm2. What does it means? bash-2.05b# lilo
Warning: Kernel & BIOS return differing head/sector geometries for device0x80Kernel: 13424 cylinders, 15 heads, 63 sectors BIOS: 788 cylinders, 255 heads, 63 sectors
It means that Kernel and BIOS each invent a fake geometry for your disk, and they did not invent the same fake geometry.
Quoted 1 line
Could it be dangerous?
No.
Linux does not use the BIOS, and does not use CHS either, so geometry is totally and completely irrelevant to Linux.
Depending on the precise LILO version, and on whether you give options like "linear" and "lba32", LILO might or might not be confused. Test whether you can boot. If booting works all is well. If not make sure you set at least one of "linear" and "lba32".
If you also have DOS on the same disk the story is more complicated. All systems on a disk must agree as to where the partitions are, or corruption will be the result.
Quoted 2 lines · Andries Brouwer
Linux does not use the BIOS, and does not use CHS either, so geometry is totally and completely irrelevant to Linux.
Is that also true for 2.2? I've had problems where large drives (60+G) do these geometry tricks, and if I don't force the geometry to what I want, fdisk (actually, sfdisk, dunno about fdisk) doesn't see the entire drive.
Sometimes the BIOS doesn't report the specific geometry that the kernel detects means "LBA" (I think this depends partly on drive firmware) and then the kernel writes out some goofy geometry to the partition table (I assume kernel geometry info is kept there?) and again I have problems accessing the entire drive.
Also, if I later change the geometry, the previous partition table seems to become incorrect. This one really confuses me, shouldn't the partition table be indexed by sectors?
Anyway, it's been a very long time since I've worked directly on this problem, so lots of my characterizations may be wrong. But I do know that we force the geometry to specific values in our install, to combat specific problems we've encountered.
/fc
Quoted 5 lines · Frank Cusack
Quoted 2 lines · Andries Brouwer
Linux does not use the BIOS, and does not use CHS either, so geometry is totally and completely irrelevant to Linux.
Is that also true for 2.2?
Yes.
Quoted 4 lines
I've had problems where large drives (60+G)
do these geometry tricks, and if I don't force the geometry to what I want, fdisk (actually, sfdisk, dunno about fdisk) doesn't see the entire drive.
Most likely you are talking about a disk soft-clipped by jumper. Some BIOSes cannot handle disks larger than 32GB, so all larger disks come with a jumper that makes the disk look like a 32GB disk. The details depend on the disk manufacturer.
A lot of details can be found in
http://www.win.tue.nl/~aeb/linux/Large-Disk-11.html#ss11.3
Followup to: <[email protected]> By author: Andries Brouwer <[email protected]> In newsgroup: linux.dev.kernel
Quoted 4 lines
Linux does not use the BIOS, and does not use CHS either, so geometry is totally and completely irrelevant to Linux.
Actually, unless you have it "linear" or "lba32", LILO *does* use CHS. Unfortunately.
-hpa
Signature · 3 lines
<[email protected]> at work, <[email protected]> in private! "Unix gives you enough rope to shoot yourself in the foot." Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64
Quoted 2 lines · H. Peter Anvin
Actually, unless you have it "linear" or "lba32", LILO *does* use CHS. Unfortunately.
Distribution makers shouldn't be overly impressed by this default, and just put "lba32" into any new lilo.conf they generate, or at least offer the option to do so.
Keeping the old CHS default makes sure that people upgrading LILO on an already configured (and probably quite ancient) system that really needs CHS don't get a nasty surprise.
- Werner
Signature · 3 lines
_________________________________________________________________________ / Werner Almesberger, Buenos Aires, Argentina [email protected] / /_http://www.almesberger.net/____________________________________________/
Quoted 6 lines · Werner Almesberger
Quoted 2 lines · H. Peter Anvin
Actually, unless you have it "linear" or "lba32", LILO *does* use CHS. Unfortunately.
Quoted 8 lines
Distribution makers shouldn't be overly impressed by this default, and just put "lba32" into any new lilo.conf they generate, or at least offer the option to do so.
Keeping the old CHS default makes sure that people upgrading LILO on an already configured (and probably quite ancient) system that really needs CHS don't get a nasty surprise.
Presumably "linear", not "lba32". I *presume* LILO has enough wherewithal to use EBIOS if it's available and fall back to CBIOS otherwise for at least one of these options. I at least thought "lba32" would force EBIOS usage.
-hpa
Quoted 4 lines · H. Peter Anvin
Presumably "linear", not "lba32". I *presume* LILO has enough wherewithal to use EBIOS if it's available and fall back to CBIOS otherwise for at least one of these options. I at least thought "lba32" would force EBIOS usage.
Yes, that seems to be the case. (All the LBA32 code is from John Coffman. I've copied him in case he's interested in the thread.) But you're still betting on the BIOS to either implement EDD correctly, or at least to report that it doesn't support it.
Call me paranoid, but I wouldn't be at all surprised if there are some BIOSes out there that get this wrong.
- Werner
Signature · 3 lines
_________________________________________________________________________ / Werner Almesberger, Buenos Aires, Argentina [email protected] / /_http://www.almesberger.net/____________________________________________/
Quoted 5 lines · Werner Almesberger
Quoted 1 line · H. Peter Anvin
Presumably "linear", not "lba32". I *presume* LILO has enough wherewithal to use EBIOS if it's available and fall back to CBIOS otherwise for at least one of these options. I at least thought "lba32" would force EBIOS usage.
Quoted 8 lines
Yes, that seems to be the case. (All the LBA32 code is from John Coffman. I've copied him in case he's interested in the thread.) But you're still betting on the BIOS to either implement EDD correctly, or at least to report that it doesn't support it.
Call me paranoid, but I wouldn't be at all surprised if there are some BIOSes out there that get this wrong.
Well... it's somewhat unlikely given the sheer amount of things that would probably break. The rule these days is that if it works with the particular versin of M$ that's currently shipping then it's good, but I'm pretty sure NTLOADER uses EDD.
-hpa
Quoted 5 lines · H. Peter Anvin
Quoted 4 lines · Werner Almesberger
Quoted 1 line · H. Peter Anvin
Presumably "linear", not "lba32". I *presume* LILO has enough wherewithal to use EBIOS if it's available and fall back to CBIOS otherwise for at least one of these options. I at least thought "lba32" would force EBIOS usage.
Quoted 8 lines
Quoted 6 lines
Yes, that seems to be the case. (All the LBA32 code is from John Coffman. I've copied him in case he's interested in the thread.) But you're still betting on the BIOS to either implement EDD correctly, or at least to report that it doesn't support it. Call me paranoid, but I wouldn't be at all surprised if there are some BIOSes out there that get this wrong.
Well... it's somewhat unlikely given the sheer amount of things that would probably break. The rule these days is that if it works with the particular versin of M$ that's currently shipping then it's good, but I'm pretty sure NTLOADER uses EDD.
Likewise GRUB.
Win 95 & 98 require EDD.
Win NT, 2000, and XP use it to boot (NTLDR).
--John
PGP encrypted e-mail preferred (www.pgpi.com) My KeyID: 178A1C6B (good until 31-Dec-2004) Keyserver at ldap://keyserver.pgp.com LILO links at http://freshmeat.net/projects/lilo