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From: Palmer Dabbelt <palmer@sifive.com>
To: linux-riscv@lists.infradead.org
Cc: Palmer Dabbelt <palmer@sifive.com>
Subject: [PATCH 1/4] Documentation: riscv: boot: We're not compatible with arm64
Date: Fri, 13 Sep 2019 12:24:30 -0700
Message-ID: <20190913192433.4316-2-palmer@sifive.com> (raw)
In-Reply-To: <20190913192433.4316-1-palmer@sifive.com>

The documentation for our bootloader claims that it can be made
compatible with arm64, but that's not true.  There are some differences
between our format and arm64:

* We've used the first 32 bits of their 64-bit "res2" as a version number,
  which we're currently setting to non-zero.
* We're using their "res4" field as our magic number.
* We're treating their magic number as our "res3" field, which nominally
  contains a flag for big endian systems already.  This can't get set, so we
  should just drop it -- it's also not described what the flag means.

This patch removes the claim that our header can be made compatible with
arm64.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
---
 Documentation/riscv/boot-image-header.txt | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Documentation/riscv/boot-image-header.txt b/Documentation/riscv/boot-image-header.txt
index 1b73fea23b39..77e8e505bc41 100644
--- a/Documentation/riscv/boot-image-header.txt
+++ b/Documentation/riscv/boot-image-header.txt
@@ -21,9 +21,8 @@ The following 64-byte header is present in decompressed Linux kernel image.
 	u32 res3;		  /* Reserved for additional RISC-V specific header */
 	u32 res4;		  /* Reserved for PE COFF offset */
 
-This header format is compliant with PE/COFF header and largely inspired from
-ARM64 header. Thus, both ARM64 & RISC-V header can be combined into one common
-header in future.
+This header format is compliant with PE/COFF header and largely inspired by,
+but not compatible with, the ARM64 header.
 
 Notes:
 - This header can also be reused to support EFI stub for RISC-V in future. EFI
-- 
2.21.0


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Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 19:24 [PATCH 0/4] Documentation: riscv: Image cleanups Palmer Dabbelt
2019-09-13 19:24 ` Palmer Dabbelt [this message]
2019-09-14  1:13   ` [PATCH 1/4] Documentation: riscv: boot: We're not compatible with arm64 Paul Walmsley
2019-09-14  2:46     ` Atish Patra
2019-09-13 19:24 ` [PATCH 2/4] Documentation: riscv: boot: Don't claim we're compliant with PE Palmer Dabbelt
2019-09-13 19:24 ` [PATCH 3/4] Documentation: riscv: boot: Whitespace fix Palmer Dabbelt
2019-09-13 19:24 ` [PATCH 4/4] Documentation: riscv: boot: Don't mention big-endian Palmer Dabbelt
2019-09-14  4:06 ` [PATCH 0/4] Documentation: riscv: Image cleanups Atish Patra

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