linux-kernel - Re: [PATCH] arm64: head: set TEXT

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Message-ID: <fabf130b-72e4-4aaa-8570-b6b8378c09a7@ixit.cz>
Date: Mon, 6 Oct 2025 12:20:07 +0200
From: David Heidelberg <david@...t.cz>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH] arm64: head: set TEXT_OFFSET to the historical value

Hi.

So far, only Pixel 3 and 3 XL with "recent" bootloaders are affected.

As I see it, the cost of making it compatible is accepting the commit at 
zero maintenance or runtime cost.

Would make sense to also update the comment in the code to reflect the 
change?

Thank you!

Reviewed-by: David Heidelberg <david@...t.cz>


On 06/10/2025 00:21, Dmitry Baryshkov wrote:
> From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 
> Historically arm64 kernel contained (almost fixed) value of 0x8000 at
> the TEXT_OFFSET. The commit cfa7ede20f13 ("arm64: set TEXT_OFFSET to 0x0
> in preparation for removing it entirely") and then commit 120dc60d0bdb
> ("arm64: get rid of TEXT_OFFSET") replaced this field with 0.
> 
> This caused no problems so far, because nobody seemed to be playing with
> the extremely picky Qualcomm bootloader as used on some of Google Pixel
> phones. Current attempting to boot the Linux kernel on those devices
> will fail to load on those phones with the following message:
> 
> KernelDecompress failed: Invalid Parameter Kernel TextOffset does not match
> Error calling BootPrepareAsync Invalid Parameter
> 
> Since the kernel ignores the field, set it to the expected value of
> 0x8000, unbreaking boot of upstream kernels on Qualcomm devices.
> 
> Note: I purposedly didn't add Fixes tags, since those commits didn't
> break any of devices that were supported at that time.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> ---
>   arch/arm64/kernel/head.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index ca04b338cb0d173f6d9f5bcee52f6d3d06552599..05e874977de376835625f52bfdda78305dca28b5 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -60,7 +60,7 @@
>   	 */
>   	efi_signature_nop			// special NOP to identity as PE/COFF executable
>   	b	primary_entry			// branch to kernel start, magic
> -	.quad	0				// Image load offset from start of RAM, little-endian
> +	.quad	0x80000				// Image load offset from start of RAM, little-endian
>   	le64sym	_kernel_size_le			// Effective size of kernel image, little-endian
>   	le64sym	_kernel_flags_le		// Informative flags, little-endian
>   	.quad	0				// reserved
> 
> ---
> base-commit: bd773c01d149aec064ea0fc890a54be277acfa3b
> change-id: 20251006-arm64-text-offset-a45fee505c4d
> 
> Best regards,

-- 
David Heidelberg