Date: Thu, 13 Dec 2018 09:37:12 -0700 From: Ian Lepore <ian@freebsd.org> To: Warner Losh <imp@bsdimp.com>, Mark Martinec <Mark.Martinec+freebsd@ijs.si> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: zfsboot@12.0: Shortening read at xxxx from 16 to -479991569 Message-ID: <1544719032.55242.25.camel@freebsd.org> In-Reply-To: <CANCZdfpKW7ko-2snguHjTGixrLGt6Cw6mGEcPfHVi4HkCEgr_Q@mail.gmail.com> References: <eb59bd1f55f6df8c9a5f4c6b2cac914a@ijs.si> <CANCZdfpKW7ko-2snguHjTGixrLGt6Cw6mGEcPfHVi4HkCEgr_Q@mail.gmail.com>
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On Thu, 2018-12-13 at 08:59 -0700, Warner Losh wrote:
> On Thu, Dec 13, 2018, 6:19 AM Mark Martinec <Mark.Martinec+freebsd@ij
> s.si
> wrote:
>
> >
> > On one of my hosts (now running 12.0-RELEASE) the zfsboot shows
> > this weird negative number, which sounds suspicious:
> >
> > Verifying DMI pool Data .............
> > Shortening read at 3907029152 from 16 to 15
> > Shortening read at 7435283708 from 16 to -479991569
> >
> > BTX loader 1.0 BTX version is 1.02
> > Consoles: ...
> > BIOS drive C: is disk0
> > ...
> >
> > The machine boots up normally and is fine, zpool scrub is happy,
> > so, should I worry? Anything fishy there?
> >
> > Searching through sources, the message seems to come from
> > stand/i386/zfsboot/zfsboot.c :
> >
> > printf("Shortening read at %lld from %d to %lld\n",
> > alignlba, alignnb, (zdsk->dsk.size + zdsk->dsk.start) -
> > alignlba);
> >
>
> Do you have any encrypted disks?
>
> Warner
I ran into something like this once before, and tracked it down to
using the roundup2() and rounddown2() macros from sys/param.h. In
particular, a mix of 32 and 64 bit types of different signedness
resulted in zero-extension instead of sign-extension of one of the
values, and that masked off significant bits, then a later subtraction
turned a result into a negative number.
-- Ian
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