Followup to: <[EMAIL PROTECTED]>
By author: OKUJI Yoshinori <[EMAIL PROTECTED]>
In newsgroup: linux.dev.kernel
>
> I don't think what GRUB does is a wrong thing basically. Some types
> of software always need (or want) to access raw devices, for example,
> FDISK programs, filesystem resizers, and fast database servers. So,
> AFAIK, all the realistic operating systems export raw devices to
> user-level programs and support one or more system calls to keep
> anything in the kernel consistent.
>
That's a pretty ridiculous assertion! When you have a kernel
filesystem mounted, it belongs to the kernel. However, in the past
Linux has allowed the boot block -- not being used by the in-kernel
filesystem -- to be accessed via the block device. Breaking this
without introducing an API to write the boot block was a bad idea.
> For now, the grub shell calls sync() (twice before any operation)
> and ioctl(fd, BLKFLSBUF, 0) (after and before operations) under
> Linux. I thought that was enough, since sync should make filesystems
> and buffer caches consistent, and BLKFLSBUF should flush buffer caches
> to actual disks. I even thought that was overkill.
There operations don't change a thing. At all. They're not merely
overkill, they're useless. You're changing tires because you're out
of gas.
-hpa
--
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"Unix gives you enough rope to shoot yourself in the foot."
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