And the reason why is because the MBR is tiny, and has no room for code that reads say, ext4.
The MBR doesn't need to read a filesystem. It's good enough that a partition boot sector does it. And if your filesystem is so complex that it needs more than 510 bytes of code to read a small file, you're using the wrong filesystem for a bootloader (or entirely).
The MBR has no menu. The basic stuff is "find active partition, load first sector, jump to it".
Maybe Grub doesn't. I was pointing out that my experimental MBR bootloader did the same but first presented a menu.
If you're thinking grub should load the code from some fixed space in the Linux partition, then every single FS would have to agree to reserve that space. Including the ones like JFS that come from elsewhere.
Argh. No. Your boot sector is stored in the first sector of your boot partition and it reads as appropriate for that filesystem. If you don't want to have a dedicated system/boot partition, you can shift the original boot sector somewhere into the filesystem if enough of it isn't needed after initial boot.
In my understanding, a partition having a boot sector is a DOS convention, that other filesystems don't necessarily follow.
That might be a problem. But if you're going to use arcane filesystems, have a separate system/boot partition. It's really no problem except, as you suggest, if you have (1) an old/buggy BIOS which can only read from the start of the drive; and (2) some reason you can't relocate + renumber partitions. Is this a problem for any PC built in the past decade?
If you mean a special, reserved partition, then that reduces the number of primary partitions for other purposes to 3, which creates compatibility issues. And if there are 4 primary ones already, you're screwed.
For the n'th time, there is no reason you can't boot from a logical partition. If you already have 4 primary partitions, convert one to a logical partition.
So we're left with the case where you already have 4 partitions containing operating systems which cannot boot from an extended partition, each with a filesystem which requires the full content of the first sector other than during boot, and each sufficiently complex that it cannot be read with MBR code. Cases?
No you don't. GRUB will compute the blocks and store them in the MBR. It's "unreliable" because if the file to be loaded is physically moved/modified, the loader will be broken.
I wasn't imagining that I was forced to manually type out a list of blocks occupied by the file. But I was concerned by exactly what you say. Dear God, why do it like that?
I bet you mean that you wrote a program to which you gave the path of a COM file that would in turn write the MBR so it would load and execute that file.
The MBR did the boot menu and loaded the boot sector from any given partition. That boot sector would do as you say. You don't need to "bet" - it's pretty much what I said:-).
And it happened to work with your BIOS and the files you tried it with
Well, it happened to work on half a dozen machines built over the past 12 years and every VM I tried it on.
did you try with files physically located after 8GiB ?
Yes. This isn't 1995 any more. INT 13 extensions are supported.
on an old broken BIOS ?)
Probably not. What kind of old and broken are you contemplating?
So what ? That's basically what LILO and GRUB stage 1 are doing.
Really? So why does GRUB need any extra-partition space?
Could you really boot an extended partition ?
Why wouldn't you be able to retrieve the boot sector of an extended partition? Obviously some operating systems (Windows) will assume they're booting off a primary partition and break unless their boot sector is tweaked, but this isn't inevitable.
GRUB is a shell, understand many filesystems, can boot a variety of OS (many of which are requiring multiple files being loaded at specific addresses), from a variety of devices (including netboot), does switch to protected mode, and much more. It happens that all these features are not fitting in the at most 446 bytes available in the MBR.
Which is why it should load a second stage from a system or other partition.
What's wrong with FAT? Pretty much everything from space inefficiency to lack of permissions to filename restrictions to reliability issues, especially after unclean shutdowns.
Why does your bootloader partition need to concern itself with space efficiency, permissions and filename restrictions? And why are you not doing synchronous writes to critical areas, ordered such that no single sector write will corrupt a file? I doubt Grub replays the journal before boot, so journaling won't help.
Finally, please explain why a non-standard storage in unpartitioned space solves any of the listed problems.
Put another way, explain why EFI is wrong to use FAT and say what should have been done.
Could it be something to do with the fact that people aren't booting from FAT filesystems?
So what's wrong with a FAT system partition? And, no, you don't need to boot from a primary partition. As a bonus, you can manipulate your boot settings just by fiddling with files in the regular filesystem in the regular partition.
particularly if you have to support all of them.
You only need to do initial boot from one filesystem, and you only need to install support for bootloading from that filesystem.
There is not a 4 partition limit. MBR allows infinite partitions (space-permitting) within the extended partition - even more than GPT, in theory.
And there is no reason you can't boot from a logical partition - it's just a problem for Windows because of the way it computes distances from the start of extended partition vs whole disk, and that can be fixed by fiddling with the boot sector for the partition.
What's to prevent one of these programs from overwriting the data another makes?
Nothing should be doing it. But what's happening here is some badly behaving Windows program exposing a fault in Grub. The article title is misleading.
Wait wait wait, I have to specify the specific blocks to load now? And grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and its use is discouraged. grub-setup: error: If you really want blocklists, use --force....?
I've written a toy partition bootloader over a weekend which was able in around 400 bytes to load and execute any file on a FAT filesystem. And another for the MBR gave a menu of primary and extended partitions for keyboard selection. What is the Grub project finding so difficult?
The "boot block" is precisely one sector right at the start of the fixed disk, with some space being taken up by the primary partition table, signature, etc. The problem is not Grub (and certain Windows software) writing to this area, but writing to unpartitioned space elsewhere on the drive.
This is as wrong as looking at some filesystem, discovering that certain free blocks are unlikely to be allocated, and then using that space for storage.
Bingo. It is absolutely wrong to put data outside of partitioned space, and it is insane to blame something else for your own bug. Indeed, one security measure when installing a new system might be to zero out all unpartitioned space and then make sure nothing is ever written to it - Grub makes this impossible.
Grub should use an existing partition to store all the bits which don't fit inside the MBR, following the lead of EFI system partitions if necessary but supporting various common filesystems otherwise. Instead they use an atrocious hack to try to make things look neat.
only females under 35 and weighing under 150 pounds
At least someone's thinking of the (female) children!
For everyone else, there's NAMBLA Card.
I have no idea why I just typed that.
I'm sorry.
I'm going to post this anyway just as an experiment to see how I get modded.
Also, this is, "If you have done nothing wrong, you have nothing to hide!" taken to its inevitable conclusion.
So I agree with you, except that it should compulsion should only apply to the families of those who support such government "protection".
Because who wins out when the only way to protect yourself from terrorist bogeymen is to have hordes of paedophile bogeymen looking at your family naked?
No, just construct a specious argument that the Constitution/Amendment doesn't apply to this case. And ensure over time that the group of gentlefolk who get to strike down unconstitutional laws agree suspiciously often with you.
That's how the US government's got away with it to now.
Dude, you haven't shown yourself to being even remotely competent, informed, or rational in your own stupid, anti-whatever that doesn't suit you post.
Your post seems to be a combination of good points and random aggressive swipes. You remind me of a PTSD sufferer repeatedly encountering a trigger.
I wasn't anti-anything except democratically elected representatives doing other than representing a knowledgeable electorate. Do you think that representatives should be acting in their own interests?
Well, I stopped taking any geography when I was 13, such choice being a luxury of a non-National-Curriculum school. Some of what came under geography, e.g. resource mining and the worker issues surrounding it, was very interesting to me. But labelling of countries was not stimulating. I remember doing the British equivalent of memorising all the English counties etc. one evening, but today I have to, "Where's that?" for most of them. My brain just doesn't care what or where Northumbria (Northumberland?) and Wessex are. Perhaps it's related that I also hate jargon for its own sake - there seems to be so much of it now computing has become "cool". In both cases, it's all political/marketing.
However, I don't think people mock the US citizens simply because they are ignorant about the world. The frustration arises because US citizens are ignorant about the world while its elected government exerts tremendous influence on the world. If your democracy is at war, something is very wrong if a lot of citizens don't know where most of the troops are deployed (I would say "which country you're fighting against" but we're having one of those 1984 style wars against no-one and everyone). If your representatives think that Iran is a menace and potentially a good target for war, it should be because you (as a group) generally think the same. If you know nothing about Iran except that women don't get to wear bikinis and that Ahmadinejad hates Israel, something is broken.
I'd spend hours on some homework problems that had typos in them
Me too. And sometimes it was because I was too stubborn to read the errata until I'd absolutely proven that the text/question/answer must be flawed. But I'm not recommending that beginners should read originals without a commentary, nor that they should be as stubborn as I was/am.
Of course, sometimes a commentary is misguided, and as you advance you'll have fun challenging that.
Some college kids have to work more than one job, you know.
That's an administrative problem, not an academic one. Some people have no money/time for university at all, but that doesn't necessarily mean there's something wrong with the concept of university study.
Yes, I would say that it's worth learning Latin (during your early school years). You won't remember all the words through adulthood but you'll get a good grounding in general language principles, all Romance languages and half of English.
And you'll be able to read some of the classics without the rhythm and subtleties lost in translation.
Maybe it's because I've been on the 'net through the late '90s, (maybe because I just wrote it,) but I could read that with no problem. Even if I wasn't aware of leetspeak, it would be one of the most trivial things to interpret - probably because I know how to read which means knowing how to decipher symbols which are similar to but not quite the same as I'm used to, and I've done enough cryptography as part of mathematical training to "see" a letter substitution cipher of plain English. No "special training" required.
We're both promoting the same thing. It's pointless to read original manuscripts in cursive.
This may be true for the average reader providing someone else has created a sufficiently good typeset version. But, because that only applies in a small number of documents vs the number of scribbled documents that have ever been produced and are being produced right now, it is important to know how to read.
If I were a high-schooler who wanted to learn calculus from say Leibniz's manuscripts, I'd be also tripping on mistakes in his manuscript.
Why wouldn't a high schooler want to see mistakes? Of course it is valuable to be read with an accompanying commentary which highlights them, but I would still want them there. I want to know where people went wrong, both in trivial and conceptual terms, so I can see how thought has developed and what excellent human minds are able (and not able) to do.
People like to elevate the greats of science and mathematics to some position of heroic infallibility. They turn education into the recitation of certain precise formulations of their work (more precise than the person who actually put in the creative effort could manage), without the requirement to really understand it. People are put off really learning anything. You can help avoid this by taking people as close to the source as possible, warts and all.
The simple truth is that the useful information is the data, not the presentation
Information is useless if it is not presented in an understandable way, and information is better processed when it is better presented. "Better" depends on the circumstances.
Every time I wonder why Apple and Google are doing so well I recall just how fucking stupid most geeks are not to recognise this.
I'm hardly pushing the boundaries
And you will continue to not push the boundaries while you expect everyone to Reader's Digest the world for you.
it would still be hours of work for me to decrypt, say, my great-grandmother's letters. It's a specialised skill.
How do you think people read anything beyond published books for the past few hundred years? It is not a "specialised skill" unless you're considering production and study of calligraphy for its own sake.
The skill of reading, i.e. recognising repeated patterns in adjacent word-forming symbols, is not the same as the act of memorising the anatomy of a cat.
The value of understanding the motivations and thought processes of the inventor of some concept or piece of technology by reading his original words is not the same as the act of memorising the anatomy of a cat.
Your cat is made of straw.
There's a poster above you who explained quite clearly that Feynman was keen to understand context and application, which is what I am trying to promote.
Slashdot Mirror
And the reason why is because the MBR is tiny, and has no room for code that reads say, ext4.
The MBR doesn't need to read a filesystem. It's good enough that a partition boot sector does it. And if your filesystem is so complex that it needs more than 510 bytes of code to read a small file, you're using the wrong filesystem for a bootloader (or entirely).
The MBR has no menu. The basic stuff is "find active partition, load first sector, jump to it".
Maybe Grub doesn't. I was pointing out that my experimental MBR bootloader did the same but first presented a menu.
If you're thinking grub should load the code from some fixed space in the Linux partition, then every single FS would have to agree to reserve that space. Including the ones like JFS that come from elsewhere.
Argh. No. Your boot sector is stored in the first sector of your boot partition and it reads as appropriate for that filesystem. If you don't want to have a dedicated system/boot partition, you can shift the original boot sector somewhere into the filesystem if enough of it isn't needed after initial boot.
In my understanding, a partition having a boot sector is a DOS convention, that other filesystems don't necessarily follow.
That might be a problem. But if you're going to use arcane filesystems, have a separate system/boot partition. It's really no problem except, as you suggest, if you have (1) an old/buggy BIOS which can only read from the start of the drive; and (2) some reason you can't relocate + renumber partitions. Is this a problem for any PC built in the past decade?
If you mean a special, reserved partition, then that reduces the number of primary partitions for other purposes to 3, which creates compatibility issues. And if there are 4 primary ones already, you're screwed.
For the n'th time, there is no reason you can't boot from a logical partition. If you already have 4 primary partitions, convert one to a logical partition.
So we're left with the case where you already have 4 partitions containing operating systems which cannot boot from an extended partition, each with a filesystem which requires the full content of the first sector other than during boot, and each sufficiently complex that it cannot be read with MBR code. Cases?
Well, some deployment software explicitly zeroes out unpartitioned space. That makes sense.
But I don't think flexlm or whatever it's called today has any business there.
Sometimes it takes badly behaving software to expose faults with other software.
No you don't. GRUB will compute the blocks and store them in the MBR. It's "unreliable" because if the file to be loaded is physically moved/modified, the loader will be broken.
I wasn't imagining that I was forced to manually type out a list of blocks occupied by the file. But I was concerned by exactly what you say. Dear God, why do it like that?
I bet you mean that you wrote a program to which you gave the path of a COM file that would in turn write the MBR so it would load and execute that file.
The MBR did the boot menu and loaded the boot sector from any given partition. That boot sector would do as you say. You don't need to "bet" - it's pretty much what I said :-).
And it happened to work with your BIOS and the files you tried it with
Well, it happened to work on half a dozen machines built over the past 12 years and every VM I tried it on.
did you try with files physically located after 8GiB ?
Yes. This isn't 1995 any more. INT 13 extensions are supported.
on an old broken BIOS ?)
Probably not. What kind of old and broken are you contemplating?
So what ? That's basically what LILO and GRUB stage 1 are doing.
Really? So why does GRUB need any extra-partition space?
Could you really boot an extended partition ?
Why wouldn't you be able to retrieve the boot sector of an extended partition? Obviously some operating systems (Windows) will assume they're booting off a primary partition and break unless their boot sector is tweaked, but this isn't inevitable.
GRUB is a shell, understand many filesystems, can boot a variety of OS (many of which are requiring multiple files being loaded at specific addresses), from a variety of devices (including netboot), does switch to protected mode, and much more.
It happens that all these features are not fitting in the at most 446 bytes available in the MBR.
Which is why it should load a second stage from a system or other partition.
What's wrong with FAT? Pretty much everything from space inefficiency to lack of permissions to filename restrictions to reliability issues, especially after unclean shutdowns.
Why does your bootloader partition need to concern itself with space efficiency, permissions and filename restrictions? And why are you not doing synchronous writes to critical areas, ordered such that no single sector write will corrupt a file? I doubt Grub replays the journal before boot, so journaling won't help.
Finally, please explain why a non-standard storage in unpartitioned space solves any of the listed problems.
Put another way, explain why EFI is wrong to use FAT and say what should have been done.
Could it be something to do with the fact that people aren't booting from FAT filesystems?
So what's wrong with a FAT system partition? And, no, you don't need to boot from a primary partition. As a bonus, you can manipulate your boot settings just by fiddling with files in the regular filesystem in the regular partition.
particularly if you have to support all of them.
You only need to do initial boot from one filesystem, and you only need to install support for bootloading from that filesystem.
There is not a 4 partition limit. MBR allows infinite partitions (space-permitting) within the extended partition - even more than GPT, in theory.
And there is no reason you can't boot from a logical partition - it's just a problem for Windows because of the way it computes distances from the start of extended partition vs whole disk, and that can be fixed by fiddling with the boot sector for the partition.
What's to prevent one of these programs from overwriting the data another makes?
Nothing should be doing it. But what's happening here is some badly behaving Windows program exposing a fault in Grub. The article title is misleading.
Wait wait wait, I have to specify the specific blocks to load now? And ...?
grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and its use is discouraged.
grub-setup: error: If you really want blocklists, use --force.
I've written a toy partition bootloader over a weekend which was able in around 400 bytes to load and execute any file on a FAT filesystem. And another for the MBR gave a menu of primary and extended partitions for keyboard selection. What is the Grub project finding so difficult?
The "boot block" is precisely one sector right at the start of the fixed disk, with some space being taken up by the primary partition table, signature, etc. The problem is not Grub (and certain Windows software) writing to this area, but writing to unpartitioned space elsewhere on the drive.
This is as wrong as looking at some filesystem, discovering that certain free blocks are unlikely to be allocated, and then using that space for storage.
Bingo. It is absolutely wrong to put data outside of partitioned space, and it is insane to blame something else for your own bug. Indeed, one security measure when installing a new system might be to zero out all unpartitioned space and then make sure nothing is ever written to it - Grub makes this impossible.
Grub should use an existing partition to store all the bits which don't fit inside the MBR, following the lead of EFI system partitions if necessary but supporting various common filesystems otherwise. Instead they use an atrocious hack to try to make things look neat.
1. Serious engineers use HP calculators;
2. Cushioned innards no?
only females under 35 and weighing under 150 pounds
At least someone's thinking of the (female) children!
For everyone else, there's NAMBLA Card.
I have no idea why I just typed that.
I'm sorry.
I'm going to post this anyway just as an experiment to see how I get modded.
Also, this is, "If you have done nothing wrong, you have nothing to hide!" taken to its inevitable conclusion.
So I agree with you, except that it should compulsion should only apply to the families of those who support such government "protection".
Because who wins out when the only way to protect yourself from terrorist bogeymen is to have hordes of paedophile bogeymen looking at your family naked?
Another single sentence paragraph.
Well, sentence fragment!
No, just construct a specious argument that the Constitution/Amendment doesn't apply to this case. And ensure over time that the group of gentlefolk who get to strike down unconstitutional laws agree suspiciously often with you.
That's how the US government's got away with it to now.
Dude, you haven't shown yourself to being even remotely competent, informed, or rational in your own stupid, anti-whatever that doesn't suit you post.
Your post seems to be a combination of good points and random aggressive swipes. You remind me of a PTSD sufferer repeatedly encountering a trigger.
I wasn't anti-anything except democratically elected representatives doing other than representing a knowledgeable electorate. Do you think that representatives should be acting in their own interests?
As a half-Spaniard, I wholeheartedly apologise to myself for the need of the other half of me to cling on to the last vestiges of our dead Empire.
OK, no, Argentina's not Spain either. So I also apologise for the other other half's initial incursion and legacy to the extent that it is not wanted.
I'm too young to have consciously objected to either at the time, but I want to know about it because I don't want the behaviour repeated.
So was it a good thing or a bad thing when Microsoft did a Google (or rather...) with their version of Java?
If you are lucky you will target 20% of the audience on average during the presentation.
Is the proportion of British soldiers in US military presentations usually that large?
*ducks*
(literally)
(-1, Flamebait)
(literally)
*ducks again*
Well, I stopped taking any geography when I was 13, such choice being a luxury of a non-National-Curriculum school. Some of what came under geography, e.g. resource mining and the worker issues surrounding it, was very interesting to me. But labelling of countries was not stimulating. I remember doing the British equivalent of memorising all the English counties etc. one evening, but today I have to, "Where's that?" for most of them. My brain just doesn't care what or where Northumbria (Northumberland?) and Wessex are. Perhaps it's related that I also hate jargon for its own sake - there seems to be so much of it now computing has become "cool". In both cases, it's all political/marketing.
However, I don't think people mock the US citizens simply because they are ignorant about the world. The frustration arises because US citizens are ignorant about the world while its elected government exerts tremendous influence on the world. If your democracy is at war, something is very wrong if a lot of citizens don't know where most of the troops are deployed (I would say "which country you're fighting against" but we're having one of those 1984 style wars against no-one and everyone). If your representatives think that Iran is a menace and potentially a good target for war, it should be because you (as a group) generally think the same. If you know nothing about Iran except that women don't get to wear bikinis and that Ahmadinejad hates Israel, something is broken.
$529
I'd spend hours on some homework problems that had typos in them
Me too. And sometimes it was because I was too stubborn to read the errata until I'd absolutely proven that the text/question/answer must be flawed. But I'm not recommending that beginners should read originals without a commentary, nor that they should be as stubborn as I was/am.
Of course, sometimes a commentary is misguided, and as you advance you'll have fun challenging that.
Some college kids have to work more than one job, you know.
That's an administrative problem, not an academic one. Some people have no money/time for university at all, but that doesn't necessarily mean there's something wrong with the concept of university study.
Yes, I would say that it's worth learning Latin (during your early school years). You won't remember all the words through adulthood but you'll get a good grounding in general language principles, all Romance languages and half of English.
And you'll be able to read some of the classics without the rhythm and subtleties lost in translation.
Maybe it's because I've been on the 'net through the late '90s, (maybe because I just wrote it,) but I could read that with no problem. Even if I wasn't aware of leetspeak, it would be one of the most trivial things to interpret - probably because I know how to read which means knowing how to decipher symbols which are similar to but not quite the same as I'm used to, and I've done enough cryptography as part of mathematical training to "see" a letter substitution cipher of plain English. No "special training" required.
We're both promoting the same thing. It's pointless to read original manuscripts in cursive.
This may be true for the average reader providing someone else has created a sufficiently good typeset version. But, because that only applies in a small number of documents vs the number of scribbled documents that have ever been produced and are being produced right now, it is important to know how to read.
If I were a high-schooler who wanted to learn calculus from say Leibniz's manuscripts, I'd be also tripping on mistakes in his manuscript.
Why wouldn't a high schooler want to see mistakes? Of course it is valuable to be read with an accompanying commentary which highlights them, but I would still want them there. I want to know where people went wrong, both in trivial and conceptual terms, so I can see how thought has developed and what excellent human minds are able (and not able) to do.
People like to elevate the greats of science and mathematics to some position of heroic infallibility. They turn education into the recitation of certain precise formulations of their work (more precise than the person who actually put in the creative effort could manage), without the requirement to really understand it. People are put off really learning anything. You can help avoid this by taking people as close to the source as possible, warts and all.
The simple truth is that the useful information is the data, not the presentation
Information is useless if it is not presented in an understandable way, and information is better processed when it is better presented. "Better" depends on the circumstances.
Every time I wonder why Apple and Google are doing so well I recall just how fucking stupid most geeks are not to recognise this.
I'm hardly pushing the boundaries
And you will continue to not push the boundaries while you expect everyone to Reader's Digest the world for you.
it would still be hours of work for me to decrypt, say, my great-grandmother's letters. It's a specialised skill.
How do you think people read anything beyond published books for the past few hundred years? It is not a "specialised skill" unless you're considering production and study of calligraphy for its own sake.
The skill of reading, i.e. recognising repeated patterns in adjacent word-forming symbols, is not the same as the act of memorising the anatomy of a cat.
The value of understanding the motivations and thought processes of the inventor of some concept or piece of technology by reading his original words is not the same as the act of memorising the anatomy of a cat.
Your cat is made of straw.
There's a poster above you who explained quite clearly that Feynman was keen to understand context and application, which is what I am trying to promote.