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From: Daniel Kiper <daniel.kiper@oracle.com>
To: grub-devel@gnu.org, xen-devel@lists.xenproject.org
Cc: jgross@suse.com, eric.snowberg@oracle.com, arvidjaar@gmail.com,
	andrew.cooper3@citrix.com, seth.goldberg@oracle.com,
	phcoder@gmail.com
Subject: [MULTIBOOT2 DOC PATCH 02/10] multiboot2: Clarify meaning of information request header tag
Date: Thu,  9 Jun 2016 22:30:36 +0200	[thread overview]
Message-ID: <1465504244-17175-3-git-send-email-daniel.kiper@oracle.com> (raw)
In-Reply-To: <1465504244-17175-1-git-send-email-daniel.kiper@oracle.com>

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 doc/multiboot.texi |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/doc/multiboot.texi b/doc/multiboot.texi
index 27e5a2f..a7e3584 100644
--- a/doc/multiboot.texi
+++ b/doc/multiboot.texi
@@ -443,15 +443,19 @@ u32[n]  | mbi_tag_types     |
 @end group
 @end example
 
-@samp{mbi_tag_types} is an array of u32 each one representing an information
-request
-If this tag is present and @samp{optional} is set to @samp{0} information
-conveyed by requested tag types must be present. If bootloader is unable
-to supply this information it must fail with an error
+@samp{mbi_tag_types} is an array of u32 each one representing an information request.
 
-Note: it doesn't garantee that any tags of type @samp{mbi_tag_types} will
-actually be present. E.g. on a videoless system even if you requested tag
-@samp{8} no tags of type @samp{8} will be present in mbi.
+If this tag is present and @samp{optional} is set to @samp{0} bootloader must
+support (understand meaning of) requested tag(s) and be able to provide relevant
+information to image if it is available. If bootloader do not understand meaning
+of requested tag(s) it must fail with an error. However, if it support a given
+tag(s) but information conveyed by it/them is not available bootloader can do not
+provide requested tag(s) in Multiboot information structure and proceed further.
+
+Note: Above means that there is not guarantee that any tags of type @samp{mbi_tag_types}
+will actually be present. E.g. on a videoless system even if you requested tag @samp{8}
+and bootloader support it no tags of type @samp{8} will be present in Multiboot
+information structure.
 
 
 @node Address header tag
-- 
1.7.10.4


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  parent reply	other threads:[~2016-06-09 20:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1465504244-17175-1-git-send-email-daniel.kiper@oracle.com>
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 01/10] multiboot2: Remove redundant if Daniel Kiper
2016-06-09 20:30 ` Daniel Kiper [this message]
2016-06-09 21:14   ` [MULTIBOOT2 DOC PATCH 02/10] multiboot2: Clarify meaning of information request header tag Andrew Cooper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 03/10] multiboot2: Fix description of EFI boot services tag Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 04/10] multiboot2: Add description of support for EFI boot services Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 05/10] multiboot2: Add description of EFI image handle tags Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 06/10] multiboot2: Add description of support for relocatable images Daniel Kiper
2016-06-09 21:36   ` Andrew Cooper
2016-06-10 17:36     ` Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 07/10] multiboot2: Say that memory maps may not be available on EFI platforms Daniel Kiper
2016-06-09 21:37   ` Andrew Cooper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 08/10] multiboot2: Add C structure alignment and padding consideration section Daniel Kiper
2016-06-09 22:07   ` Andrew Cooper
     [not found]   ` <1c1e54de-2f19-20b6-b8c8-229619b95038@citrix.com>
2016-06-10 17:58     ` Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 09/10] multiboot2: Add me to authors Daniel Kiper
2016-06-09 20:30 ` [MULTIBOOT2 DOC PATCH 10/10] multiboot2: Bump version to 2.0 Daniel Kiper
     [not found] ` <1465504244-17175-2-git-send-email-daniel.kiper@oracle.com>
2016-06-09 21:02   ` [MULTIBOOT2 DOC PATCH 01/10] multiboot2: Remove redundant if Andrew Cooper
     [not found] ` <1465504244-17175-5-git-send-email-daniel.kiper@oracle.com>
2016-06-09 21:31   ` [MULTIBOOT2 DOC PATCH 04/10] multiboot2: Add description of support for EFI boot services Andrew Cooper

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