Date: Thu, 14 Jun 2012 18:05:41 +0200 From: Olivier Smedts <olivier@gid0.org> To: "Andrey V. Elsukov" <ae@freebsd.org> Cc: current@freebsd.org Subject: Re: CFR: backup GPT header support in pmbr and loader(8) (Re: Handbook mirroring section) Message-ID: <CABzXLYMbZi78FZgUcMRUJA1a41cRaSHMDGydTz_VDnk73fHGQQ@mail.gmail.com> In-Reply-To: <4FD9EC14.8070203@FreeBSD.org> References: <4FCF3021.5070802@FreeBSD.org> <20120606.200735.1551208261335301113.hrs@allbsd.org> <4FD05573.70801@FreeBSD.org> <20120610.224813.710171778841273502.hrs@allbsd.org> <4FD9D4DF.9090609@FreeBSD.org> <CABzXLYPzgBmxGUMhbMSSa7Qxoo4pC4t8%2Bv1t_v6=9HMyP4LGmQ@mail.gmail.com> <4FD9EC14.8070203@FreeBSD.org>
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2012/6/14 Andrey V. Elsukov <ae@freebsd.org>: > On 14.06.2012 17:08, Olivier Smedts wrote: >> 2012/6/14 Andrey V. Elsukov <ae@freebsd.org>: >>> Also, our PMBR image doesn't contain any partition entries and >>> writing it to the disk with dd(1) makes the system unbootable. >>> What you think if we will add one partition entry to the PMBR image? >>> I modified your patch (the last hunk added) and it is attached. >> >> Isn't it gpart(8)'s job to write the proper boot code from the pmbr >> image without damaging the partition table ? >> >> ie. "gpart bootcode -b /boot/pmbr ada0" instead of using dd. > > gpart(8) works only when GPT's geom exists, when PMBR is damaged > GEOM_PART_GPT can't detect GPT and thus you can't use it. IMO, GEOM_PART_GPT should not depend on the MBR do detect GPT. That's the problem which should be fixed ; adding a partition to the MBR is only a workaround (and what would happen if the sector 0 was permanently damaged on disk ?). Why does GEOM_PART_GPT depends on the sector LBA 0 while the GPT header is located at sector LBA 1 ? Don't know the feasability of this, just saying... :-) --=20 Olivier Smedts=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 _ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 ASCII ribbon campaign ( ) e-mail: olivier@gid0.org=A0 =A0 =A0 =A0 - against HTML email & vCards=A0 X www: http://www.gid0.org=A0 =A0 - against proprietary attachments / \ =A0 "Il y a seulement 10 sortes de gens dans le monde : =A0 ceux qui comprennent le binaire, =A0 et ceux qui ne le comprennent pas."
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