objtool: Validate disassembler headers in libopcodes probegrafted

commit 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
tested for libopcodes availability by linking a test snippet with a forward
declaration of disassemble_init_for_target().

However, testing symbol linkage with an extern declaration only verifies
the presence of the library (.so/.a) and bypasses checking for development
headers (binutils-dev). On systems where libopcodes is present without
development headers installed, the probe succeeds, enabling BUILD_DISAS.
Subsequent compilation of objtool then fails:

  fatal error: 'bfd.h' file not found
    113 | #include <bfd.h>

Additionally, the probe invokes $(HOSTCC) without $(HOSTCFLAGS), ignoring
any sysroot or include flags specified for the host compiler.

Fix this by including <bfd.h> and <dis-asm.h> directly in the test snippet,
passing $(HOSTCFLAGS) so host compiler options are respected, and defining
PACKAGE="objtool" to satisfy the configuration check in <bfd.h>.

Fixes: 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
Fixes: 436326bc525d ("objtool: fix build failure due to missing libopcodes check")
Reported-by: Alice Ryhl <aliceryhl@google.com>
Assisted-by: Antigravity:Gemini-Next
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
Link: https://patch.msgid.link/20260904150710.2997558-1-umendez@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

1 files changed, 51 insertions, 0 deletions

diff --git a/Documentation/admin-guide/device-mapper/dm-ebs.rst b/Documentation/admin-guide/device-mapper/dm-ebs.rst
new file mode 100644
index 000000000..c09f66db5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ebs.rst
@@ -0,0 +1,51 @@
+======
+dm-ebs
+======
+
+
+This target is similar to the linear target except that it emulates
+a smaller logical block size on a device with a larger logical block
+size.  Its main purpose is to provide emulation of 512 byte sectors on
+devices that do not provide this emulation (i.e. 4K native disks).
+
+Supported emulated logical block sizes 512, 1024, 2048 and 4096.
+
+Underlying block size can be set to > 4K to test buffering larger units.
+
+
+Table parameters
+----------------
+  <dev path> <offset> <emulated sectors> [<underlying sectors>]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device,
+        or a "major:minor" device-number.
+    <offset>:
+        Starting sector within the device;
+        has to be a multiple of <emulated sectors>.
+    <emulated sectors>:
+        Number of sectors defining the logical block size to be emulated;
+        1, 2, 4, 8 sectors of 512 bytes supported.
+
+Optional parameter:
+
+    <underlying sectors>:
+        Number of sectors defining the logical block size of <dev path>.
+        2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB.
+        If not provided, the logical block size of <dev path> will be used.
+
+
+Examples:
+
+Emulate 1 sector = 512 bytes logical block size on /dev/sda starting at
+offset 1024 sectors with underlying devices block size automatically set:
+
+ebs /dev/sda 1024 1
+
+Emulate 2 sector = 1KiB logical block size on /dev/sda starting at
+offset 128 sectors, enforce 2KiB underlying device block size.
+This presumes 2KiB logical blocksize on /dev/sda or less to work:
+
+ebs /dev/sda 128 2 4