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From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi <linux-efi@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/4] EFI stub: remove -fdata-sections
Date: Tue, 6 Nov 2018 14:21:26 +0000	[thread overview]
Message-ID: <20181106142126.GD30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <CAKv+Gu_-Vqa=TXDzmzorjcPVnxqO3BHvvDyJKViHFLCsnhfeEw@mail.gmail.com>

On Tue, Nov 06, 2018 at 03:11:18PM +0100, Ard Biesheuvel wrote:
> On 6 November 2018 at 14:40, Russell King <rmk+kernel@armlinux.org.uk> wrote:
> > Remove -fdata-sections from the EFI stub build as this causes problems
> > for the ARM decompressor code.
> >
> Just out of curiosity: what kind of problems?

I'm afraid I don't remember - these patches are March 2018.  I suspect
it was a result of a randconfig build failing to link, as I don't have
any 32-bit ARM configs that have the EFI stub enabled.

In any case, this will break:

#
# ARM discards the .data section because it disallows r/w data in the
# decompressor. So move our .data to .data.efistub, which is preserved
# explicitly by the decompressor linker script.
#
STUBCOPY_FLAGS-$(CONFIG_ARM)    += --rename-section .data=.data.efistub

because with -fdata-sections enabled, there is no longer a single .data
section, but multiple .data.* sections.  Hence, the rename no longer
works, and all the EFI stub data ends up being discarded by the
decompressor link stage.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
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WARNING: multiple messages have this Message-ID (diff)
From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/4] EFI stub: remove -fdata-sections
Date: Tue, 6 Nov 2018 14:21:26 +0000	[thread overview]
Message-ID: <20181106142126.GD30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <CAKv+Gu_-Vqa=TXDzmzorjcPVnxqO3BHvvDyJKViHFLCsnhfeEw@mail.gmail.com>

On Tue, Nov 06, 2018 at 03:11:18PM +0100, Ard Biesheuvel wrote:
> On 6 November 2018 at 14:40, Russell King <rmk+kernel@armlinux.org.uk> wrote:
> > Remove -fdata-sections from the EFI stub build as this causes problems
> > for the ARM decompressor code.
> >
> Just out of curiosity: what kind of problems?

I'm afraid I don't remember - these patches are March 2018.  I suspect
it was a result of a randconfig build failing to link, as I don't have
any 32-bit ARM configs that have the EFI stub enabled.

In any case, this will break:

#
# ARM discards the .data section because it disallows r/w data in the
# decompressor. So move our .data to .data.efistub, which is preserved
# explicitly by the decompressor linker script.
#
STUBCOPY_FLAGS-$(CONFIG_ARM)    += --rename-section .data=.data.efistub

because with -fdata-sections enabled, there is no longer a single .data
section, but multiple .data.* sections.  Hence, the rename no longer
works, and all the EFI stub data ends up being discarded by the
decompressor link stage.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

  reply	other threads:[~2018-11-06 14:21 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-06 13:39 [PATCH 0/4] Enable deadcode elimination at link time Russell King - ARM Linux
2018-11-06 13:39 ` Russell King - ARM Linux
2018-11-06 13:40 ` [PATCH 1/4] EFI stub: remove -fdata-sections Russell King
2018-11-06 13:40   ` Russell King
2018-11-06 14:11   ` Ard Biesheuvel
2018-11-06 14:11     ` Ard Biesheuvel
2018-11-06 14:21     ` Russell King - ARM Linux [this message]
2018-11-06 14:21       ` Russell King - ARM Linux
2018-11-06 14:22       ` Ard Biesheuvel
2018-11-06 14:22         ` Ard Biesheuvel
2018-11-06 13:40 ` [PATCH 2/4] ARM: mark critical data with KEEP() Russell King
2018-11-06 13:40 ` [PATCH 3/4] ARM: merge -fdata-sections BSS data to .bss section Russell King
2018-11-06 14:08   ` Ard Biesheuvel
2018-11-06 14:10     ` Russell King - ARM Linux
2018-11-06 14:13       ` Ard Biesheuvel
2018-11-06 14:29         ` Russell King - ARM Linux
2018-11-06 14:39           ` Ard Biesheuvel
2018-11-06 14:45             ` Russell King - ARM Linux
2018-11-06 15:18               ` Ard Biesheuvel
2018-11-06 16:06                 ` Russell King - ARM Linux
2018-11-06 16:14                   ` Ard Biesheuvel
2018-11-06 13:40 ` [PATCH 4/4] ARM: enable LD_DEAD_CODE_DATA_ELIMINATION Russell King

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