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From: Ram Pai <linuxram@us.ibm.com>
To: The development of GNU GRUB <grub-devel@gnu.org>
Cc: phcoder@gmail.com, pfsmorigo@br.ibm.com
Subject: Re: [RFC PATCH 21/23] powerpc64 is not necessarily BigEndian anymore! :)
Date: Thu, 3 Apr 2014 10:33:36 -0700	[thread overview]
Message-ID: <20140403173336.GA16534@ram.oc3035372033.ibm.com> (raw)
In-Reply-To: <533B1FF2.9040503@gmail.com>

On Tue, Apr 01, 2014 at 10:22:10PM +0200, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> 
> > 
> > For the sake of bisectability this really should be moved earlier;
> > otherwise at least patch "fix parameter to firmware calls" would
> > be wrong.
> > 
> Even bigger problem is whether we want to run in LE mode at all. From
> what I understand (correct if I'm wrong) firmware calls remain
> big-endian and you need to switch back and forth between LE and BE when
> doing firmware calls.

Yes. firmware runs in 32bit BE mode. And there is a constant switch from
64bit LE to 32bit BE and vice-versa for each firmware call.

> doing firmware calls. Byteswapping for the purpose of firmware calls is
> to be avoided as bugs are easy to slip through (in fact the
> byte-swapping isn't complete in proposed patches.
> (correct me if I'm wrong) 

Is that true? maybe you are right. I might have missed something.
However please hint me what i have missed. I will look into some
other arch code that support the same ieee platform.


> these new patches cover a subset of already
> supported machines and don't add any user-visible feature and no new
> kernel type (LE kernel can be loaded from BE GRUB).
> Cross-compiling to BE from LE is easy (TARGET_CFLAGS=-EL).

Well. that is the issue.  Various distros have varied support for
cross-compilation (multi-arch support). If the distro does not 
have 32bit BE libraries natively installed (out-of-the-box), they
wont be able to generate a 32bit BE grub loader. These set of patches
overcomes the deficiency by generating a working native executable 
on LE systems.

> So it looks like this patch series adds a new high-maintenance-cost port
> covering only already supported machines and already supportred features.

It does add maintainence; I agree. But than it does overcome some
deficiences aswell.


Thanks for your comments. And sorry for the delay. I had not seen this
email, since i was not on copy. I will watch the mailing list regularly.
RP




> 



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> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel


-- 
Ram Pai



  reply	other threads:[~2014-04-03 17:34 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-26 18:30 [RFC PATCH 00/23] grub 64bit little-endian on power Ram Pai
2014-02-26 18:31 ` [RFC PATCH 01/23] Add a new architecture to the build process Ram Pai
2014-02-26 18:31 ` [RFC PATCH 02/23] Build LE grub as O1 Ram Pai
2014-02-26 18:31 ` [RFC PATCH 03/23] ignore .TOC. symbol Ram Pai
2014-04-01 16:52   ` Andrey Borzenkov
2014-02-26 18:31 ` [RFC PATCH 04/23] grub-install can now recognize and install a LE grub boot loader Ram Pai
2014-02-26 18:31 ` [RFC PATCH 05/23] set ABI version in e_flag of the PPC64LE ELF image Ram Pai
2014-02-26 18:31 ` [RFC PATCH 06/23] Add IEEE1275_ADDR helper Ram Pai
2014-04-01 17:11   ` Andrey Borzenkov
2014-02-26 18:31 ` [RFC PATCH 07/23] Fix some more warnings when casting Ram Pai
2014-02-26 18:31 ` [RFC PATCH 08/23] Add powerpc64 types Ram Pai
2014-04-01 17:15   ` Andrey Borzenkov
2014-04-02 17:02     ` Ram Pai
2014-02-26 18:31 ` [RFC PATCH 09/23] Fix warnings when building powerpc linux loader 64bit Ram Pai
2014-04-01 17:21   ` Andrey Borzenkov
2014-04-02 17:03     ` Ram Pai
2014-02-26 18:31 ` [RFC PATCH 10/23] GRUB_ELF_R_PPC_* processing is applicable only for 32 bit bootloader Ram Pai
2014-02-26 18:31 ` [RFC PATCH 11/23] Fix powerpc setjmp/longjmp 64bit issues Ram Pai
2014-04-01 17:27   ` Andrey Borzenkov
2014-04-02 17:06     ` Ram Pai
2014-04-02 17:19       ` Andrey Borzenkov
2014-04-02 17:48         ` Ram Pai
2014-04-02 17:56           ` Andrey Borzenkov
2014-04-02 18:55             ` Ram Pai
2014-02-26 18:31 ` [RFC PATCH 12/23] Add powerpc64 ieee1275 trampoline Ram Pai
2014-02-26 18:31 ` [RFC PATCH 13/23] Add 64bit support to powerpc startup code Ram Pai
2014-02-26 18:31 ` [RFC PATCH 14/23] Add grub_dl_find_section_addr Ram Pai
2014-02-26 18:31 ` [RFC PATCH 15/23] Add ppc64 relocations Ram Pai
2014-02-26 18:31 ` [RFC PATCH 16/23] ppc64 doesn't need libgcc routines Ram Pai
2014-02-26 18:31 ` [RFC PATCH 17/23] Use FUNC_START/FUNC_END for powerpc function definitions Ram Pai
2014-02-26 18:31 ` [RFC PATCH 18/23] .TOC. symbol is special in ppc64le Ram Pai
2014-02-26 18:31 ` [RFC PATCH 19/23] align .toc section on 4byte boundary Ram Pai
2014-02-26 18:31 ` [RFC PATCH 20/23] fix parameter to firmware calls Ram Pai
2014-04-01 17:45   ` Andrey Borzenkov
2014-04-02 17:08     ` Ram Pai
2014-04-02 17:16       ` Andrey Borzenkov
2014-02-26 18:31 ` [RFC PATCH 21/23] powerpc64 is not necessarily BigEndian anymore! :) Ram Pai
2014-04-01 17:49   ` Andrey Borzenkov
2014-04-01 20:22     ` Vladimir 'φ-coder/phcoder' Serbinenko
2014-04-03 17:33       ` Ram Pai [this message]
2014-04-03 17:53         ` Andrey Borzenkov
2014-04-03 18:37           ` Ram Pai
2014-04-03 19:03             ` Andrey Borzenkov
2014-04-03 19:26               ` Ram Pai
2014-04-03 19:42                 ` Vladimir 'φ-coder/phcoder' Serbinenko
2014-04-03 20:23                   ` Ram Pai
2014-04-03 19:54                 ` Andrey Borzenkov
2014-04-03 20:32                   ` Ram Pai
2014-04-03 21:41                     ` Vladimir 'phcoder' Serbinenko
2014-04-04  2:28                     ` Andrey Borzenkov
2014-04-04 17:47                       ` Ram Pai
2014-04-04 18:17                         ` Andrey Borzenkov
2014-04-04 18:24                           ` Dinar Valeev
2014-04-04 19:12                             ` Andrey Borzenkov
2014-04-04 20:29                               ` Dinar Valeev
2014-04-04 22:19                                 ` Ram Pai
     [not found]                                   ` <CAEaD8JN9SkqU9+BkU2MYub=aC3Wb143nMPgRWjVbFvgit90yBQ@mail.gmail.com>
2014-04-05  0:04                                     ` Fwd: " Vladimir 'phcoder' Serbinenko
2014-09-27  5:42                             ` Andrei Borzenkov
2014-09-28  6:33                               ` Andrei Borzenkov
2014-04-04  6:37                   ` Vladimir 'φ-coder/phcoder' Serbinenko
2014-04-04 17:08                     ` Andrey Borzenkov
2014-04-05 15:45                       ` Vladimir 'φ-coder/phcoder' Serbinenko
2014-04-05 16:49                         ` Andrey Borzenkov
2014-04-05 18:29                           ` Vladimir 'φ-coder/phcoder' Serbinenko
2014-04-05 18:48                             ` Andrey Borzenkov
2014-04-02 17:09     ` Ram Pai
2014-02-26 18:31 ` [RFC PATCH 22/23] fix segfaults if initrd Ram Pai
2014-02-26 18:31 ` [RFC PATCH 23/23] Optional: Power7 VSX instructions workaround Ram Pai

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