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Date: Mon, 24 Jan 2011 16:25:05 -0800
From: Mike Waychison <mikew@...gle.com>
To: Greg KH <greg@...ah.com>, torvalds@...ux-foundation.org
Cc: San Mehat <san@...gle.com>, Aaron Durbin <adurbin@...gle.com>,
Duncan Laurie <dlaurie@...gle.com>,
linux-kernel@...r.kernel.org, Tim Hockin <thockin@...gle.com>
Subject: [PATCH v1 6/6] driver: Google Memory Console
This patch introduces the 'memconsole' driver.
Our firmware gives us access to an in-memory log of the firmware's
output. This gives us visibility in a data-center of headless machines
as to what the firmware is doing.
The memory console is found by the driver by finding a header block in
the EBDA. The buffer is then copied out, and is currently prepended
to the kernel's dmesg ring-buffer.
Signed-off-by: San Mehat <san@...gle.com>
Signed-off-by: Mike Waychison <mikew@...gle.com>
---
drivers/firmware/google/Kconfig | 8 ++
drivers/firmware/google/Makefile | 1
drivers/firmware/google/memconsole.c | 136 ++++++++++++++++++++++++++++++++++
3 files changed, 145 insertions(+), 0 deletions(-)
create mode 100644 drivers/firmware/google/memconsole.c
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 0490a62..7218671 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -28,4 +28,12 @@ config GOOGLE_BOOTLOG
This enables support for displaying boot log information in dmesg
as well as logging the kernel shutdown reasons.
+config GOOGLE_MEMCONSOLE
+ bool "Firmware Memory Console"
+ default y
+ help
+ This option enables the kernel to search for a firmware log in
+ the EBDA. If found, this log is prepended to the kernel's
+ dmesg logs so they are visible to the user.
+
endmenu
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
index d45e10c..cb8598e 100644
--- a/drivers/firmware/google/Makefile
+++ b/drivers/firmware/google/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_GOOGLE_SMI) += gsmi.o
obj-$(CONFIG_GOOGLE_BOOTLOG) += bootlog.o
+obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
new file mode 100644
index 0000000..6777a64
--- /dev/null
+++ b/drivers/firmware/google/memconsole.c
@@ -0,0 +1,136 @@
+/*
+ * memconsole.c
+ *
+ * Infrastructure for importing the BIOS memory based console
+ * into the kernel log ringbuffer.
+ *
+ * Copyright 2010 Google Inc. All rights reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_MEMCONSOLE_V1_MAGIC 0xDEADBABE
+#define BIOS_MEMCONSOLE_V2_MAGIC (('M')|('C'<<8)|('O'<<16)|('N'<<24))
+
+struct biosmemcon_ebda {
+ uint32_t signature;
+ union {
+ struct {
+ uint8_t enabled;
+ uint32_t buffer_addr;
+ uint16_t start;
+ uint16_t end;
+ uint16_t num_chars;
+ uint8_t wrapped;
+ } __packed v1;
+ struct {
+ uint32_t buffer_addr;
+ /* Misdocumented as number of pages! */
+ uint16_t num_bytes;
+ uint16_t start;
+ uint16_t end;
+ } __packed v2;
+ } ptr;
+} __packed;
+
+static void __init sanitize_buffer(char *buffer, size_t length) {
+ size_t cur;
+
+ /* sanitize BIOS output by converting non-ascii into space */
+ for (cur = 0; cur < length; cur++) {
+ if (!isascii(buffer[cur]) || buffer[cur] == 0)
+ buffer[cur] = ' ';
+ }
+}
+
+/*
+ * Search through the EBDA for the BIOS Memory Console, and
+ * prepend it to our ring buffer
+ */
+static int __init inject_memconsole(void)
+{
+ static struct biosmemcon_ebda __initdata hdr = {0};
+ unsigned int address;
+ size_t length, cur;
+ uint32_t *bp;
+ char *virtp;
+ int found = 0;
+
+ address = get_bios_ebda();
+ if (!address) {
+ printk(KERN_INFO "BIOS EBDA non-existent.\n");
+ return 0;
+ }
+
+ /* EBDA length is byte 0 of EBDA (in KB) */
+ length = *(uint8_t *)phys_to_virt(address);
+ length <<= 10; /* convert to bytes */
+
+ /*
+ * Search through EBDA for BIOS memory console structure
+ * note: signature is not necessarily dword-aligned
+ */
+ for (cur = 0; cur < length; cur++) {
+ bp = phys_to_virt(address + cur);
+
+ /* memconsole v1 */
+ if (*bp == BIOS_MEMCONSOLE_V1_MAGIC) {
+ memcpy(&hdr, bp, sizeof(hdr));
+ found = 1;
+ break;
+ }
+
+ /* memconsole v2 */
+ if (*bp == BIOS_MEMCONSOLE_V2_MAGIC) {
+ memcpy(&hdr, bp, sizeof(hdr));
+ found = 2;
+ break;
+ }
+ }
+
+ /*
+ * At this point hdr points to the EBDA structure
+ * Shift the contents of the kernel ring by the size of
+ * the contents in the bios ring.
+ */
+
+ switch (found) {
+ case 1:
+ printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n",
+ bp);
+ printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+ "start = %d, end = %d, num = %d\n",
+ hdr.ptr.v1.buffer_addr, hdr.ptr.v1.start,
+ hdr.ptr.v1.end, hdr.ptr.v1.num_chars);
+
+ length = hdr.ptr.v1.num_chars;
+ virtp = phys_to_virt(hdr.ptr.v1.buffer_addr);
+ sanitize_buffer(virtp, length);
+ prepend_to_dmesg(virtp, length);
+
+ break;
+ case 2:
+ printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n",
+ bp);
+ printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+ "start = %d, end = %d, num_bytes = %d\n",
+ hdr.ptr.v2.buffer_addr, hdr.ptr.v2.start,
+ hdr.ptr.v2.end, hdr.ptr.v2.num_bytes);
+
+ length = hdr.ptr.v2.end - hdr.ptr.v2.start;
+ virtp = phys_to_virt(hdr.ptr.v2.buffer_addr + hdr.ptr.v2.start);
+ sanitize_buffer(virtp, length);
+ prepend_to_dmesg(virtp, length);
+
+ break;
+ case 0:
+ default:
+ printk("BIOS console EBDA structure not found!\n");
+ }
+ return 0;
+}
+device_initcall(inject_memconsole);
--
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