Date: Wed, 1 Nov 2006 18:43:51 +0300 From: Ruslan Ermilov <ru@FreeBSD.org> To: Bruce Evans <bde@zeta.org.au> Cc: freebsd-stable@FreeBSD.org, Stefan Bethke <stb@lassitu.de>, John Baldwin <jhb@FreeBSD.org>, Bruce Evans <bde@FreeBSD.org> Subject: Re: Still possible to directly boot without loader? Message-ID: <20061101154351.GB2247@rambler-co.ru> In-Reply-To: <20061102001337.D31271@delplex.bde.org> References: <3A8131D4-881E-4873-A682-543A1A88C063@lassitu.de> <200610261542.35322.jhb@freebsd.org> <20061026195419.GA2972@rambler-co.ru> <200610301518.20175.jhb@freebsd.org> <20061102001337.D31271@delplex.bde.org>
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--qjNfmADvan18RZcF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 02, 2006 at 12:44:56AM +1100, Bruce Evans wrote: > The masking hack is probably only needed for aout. For elf, > objdump -h /kernel says: >=20 > % Sections: > % Idx Name Size VMA LMA File off Algn > % ... > % CONTENTS, ALLOC, LOAD, READONLY, DATA > % 4 .text 002853e0 c043b510 c043b510 0003b510 2**4 >=20 > so KERNBASE =3D LMA - <File off> for at least this kernel. boot2 now > loads the text section from file offset <File off> to address LMA(masked). > I think it just needs to load at an address that is the same mod > PAGE_SIZE as LMA or VMA (these must agree mod PAGE_SIZE), provided it > adjusts the entry address to match. >=20 It isn't generally: : LINT/kernel: file format elf32-i386-freebsd :=20 : Sections: : Idx Name Size VMA LMA File off Algn : [...] : 4 .text 009c589c bf490e60 bf490e60 00090e60 2**4 : CONTENTS, ALLOC, LOAD, READONLY, CODE But: : $ nm LINT/kernel | grep kernbase : bf000000 A kernbase The "paddr" of the first loadable segment is KERNBASE + KERNLOAD, and KERNLOAD is always 2M for PAE and 4M for non-PAE. (Please see my other private email I just sent that goes into more detail about this, and provides one possible formulae to compute the KERNBASE from "paddr".) Cheers, --=20 Ruslan Ermilov ru@FreeBSD.org FreeBSD committer --qjNfmADvan18RZcF Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFSMC3qRfpzJluFF4RAjH/AJ0Tn7djdmy8yY1bUZiDfucu+cwl4gCdFyE/ pyp162Q+OwAayELO3LeE4ls= =etmQ -----END PGP SIGNATURE----- --qjNfmADvan18RZcF--
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