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From 6999f3f3ca525bb6b132f4ed804e7f8fe62e5f79 Mon Sep 17 00:00:00 2001
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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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Date: Wed, 12 Apr 2017 10:11:29 +0100
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Subject: [PATCH] lscpu: use sysfs for table access if available
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On ARM systems, accessing SMBIOS tables via /dev/mem using read()
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calls is not supported. The reason is that such tables are usually
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located in EFI_RUNTIME_SERVICE_DATA memory, which is not covered
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by the linear mapping on those systems, and so read() calls will
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fail.
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So instead, use the /sys/firmware/dmi/tables/DMI sysfs file, which
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contains the entire structure table array, and will be available
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on any recent Linux system, even on ones that only export the rev3
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SMBIOS entry point, which is currently ignored by lscpu.
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Note that the max 'num' value is inferred from the size. This is not
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a limitation of the sysfs interface, but a limitation of the rev3
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entry point, which no longer carries a number of array elements.
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Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1455664
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Upstream: http://github.com/karelzak/util-linux/commit/92a6392c41c11bcb49af9f129dfbd1fed651f044
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Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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Tested-by: Alexander Graf <agraf@suse.de>
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Reviewed-by: Alexander Graf <agraf@suse.de>
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---
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 sys-utils/lscpu-dmi.c | 16 ++++++++++++++++
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 1 file changed, 16 insertions(+)
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diff --git a/sys-utils/lscpu-dmi.c b/sys-utils/lscpu-dmi.c
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index 0e497d1..a8298ff 100644
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--- a/sys-utils/lscpu-dmi.c
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+++ b/sys-utils/lscpu-dmi.c
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@@ -192,6 +192,18 @@ static int hypervisor_decode_smbios(uint8_t *buf, const char *devmem)
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 		devmem);
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 }
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+static int hypervisor_decode_sysfw(void)
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+{
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+	static char const sys_fw_dmi_tables[] = "/sys/firmware/dmi/tables/DMI";
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+	struct stat st;
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+
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+	if (stat(sys_fw_dmi_tables, &st))
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+		return -1;
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+
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+	return hypervisor_from_dmi_table(0, st.st_size, st.st_size / 4,
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+					 sys_fw_dmi_tables);
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+}
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+
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 /*
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  * Probe for EFI interface
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  */
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@@ -242,6 +254,10 @@ int read_hypervisor_dmi(void)
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 	    || '\0' != 0)
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 		return rc;
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+	rc = hypervisor_decode_sysfw();
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+	if (rc >= 0)
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+		return rc;
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+
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 	/* First try EFI (ia64, Intel-based Mac) */
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 	switch (address_from_efi(&fp)) {
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 		case EFI_NOT_FOUND:
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-- 
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2.9.4
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