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diff --git a/sideband/internal/include/pt_sb_context.h b/sideband/internal/include/pt_sb_context.h
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+/*
+ * Copyright (c) 2017-2018, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef PT_SB_CONTEXT_H
+#define PT_SB_CONTEXT_H
+
+#include <stdint.h>
+
+struct pt_image;
+
+
+/* The ABI of the process. */
+enum pt_sb_abi {
+	pt_sb_abi_unknown,
+	pt_sb_abi_x64,
+	pt_sb_abi_x32,
+	pt_sb_abi_ia32
+};
+
+struct pt_sb_context {
+	/* The next context in a linear list of process contexts.
+	 *
+	 * I do not expect more than a few processes per tracing session.  And
+	 * if we had many processes, we'd also have trace spanning many context
+	 * switches and sideband decode won't be the bottleneck.
+	 *
+	 * This field is owned by the sideband tracing session to which this
+	 * context belongs.
+	 */
+	struct pt_sb_context *next;
+
+	/* The memory image of that process.
+	 *
+	 * You must hold a reference to this context as long as @image is used.
+	 */
+	struct pt_image *image;
+
+	/* The ABI of the process.
+	 *
+	 * This may be relevant for some but not all sideband formats.
+	 *
+	 * This field is collectively owned by all sideband decoders.
+	 */
+	enum pt_sb_abi abi;
+
+	/* We identify processes by their process id.
+	 *
+	 * Intel PT provides CR3 and VMCS Base to identify address-spaces and
+	 * notifies us about changes.  But at least on Linux, we don't get the
+	 * CR3 and all sideband records refer to pid/tid, so we're using those.
+	 */
+	uint32_t pid;
+
+	/* The number of current users.
+	 *
+	 * We remove a context when the process exits but we keep the context
+	 * object and its image alive as long as they are used.
+	 */
+	uint16_t ucount;
+};
+
+/* Allocate a context.
+ *
+ * Allocate a context and an image.  The optional @name argument is given to the
+ * context's image.
+ *
+ * The context's use-count is initialized to one.  Use pt_sb_ctx_put() to free
+ * the returned context and its image.
+ *
+ * Returns a non-NULL context or NULL when out of memory.
+ */
+extern struct pt_sb_context *pt_sb_ctx_alloc(const char *name);
+
+#endif /* PT_SB_CONTEXT_H */