Date: Wed, 20 Jun 2012 09:30:03 -0400 From: John Baldwin <jhb@freebsd.org> To: "Andrey V. Elsukov" <ae@freebsd.org> Cc: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: Re: svn commit: r237294 - user/ae/bootcode/sys/boot/i386/pmbr Message-ID: <201206200930.03176.jhb@freebsd.org> In-Reply-To: <4FE1C832.7000805@FreeBSD.org> References: <201206200829.q5K8TPcK028907@svn.freebsd.org> <201206200744.57808.jhb@freebsd.org> <4FE1C832.7000805@FreeBSD.org>
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On Wednesday, June 20, 2012 8:55:14 am Andrey V. Elsukov wrote: > On 20.06.2012 15:44, John Baldwin wrote: > >> Add one partition record to the PMBR image. It covers all space after > >> the LBA 0. It is better to have one partially correct record, than > >> have nothing. > > > > This latter part is not true. :( > > > > boot1 has a hardcoded partition in it (for use in dangerously dedicated mode). > > This has a mixed history. At one point the table entry it used caused certain > > SCSI BIOSes to crash due to a divide by zero (the SCSI BIOS read the MBR to > > try to guess what C/H/S geometry the rest of the system was expecting). I > > think having a hardcoded entry here can only really result in problems. I > > would rather you add some sort of 'restore' functionality to gpart that > > allowed it to build a PMBR 'from scratch' with a proper partition entry than > > to resort to this hack. > > AFAIK, DD mode is not supported now. Correct, because it was a disasater. Let's not create a new disaster. > As another solution we can remove checking for PMBR partition type existence > when detecting GPT (like the kernel does). I think adding a suitable command to gpart to let it recover a disk is the way to go. -- John Baldwin
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