From: Daniel Kiper Date: Thu, 9 Jun 2016 19:40:25 +0000 (+0200) Subject: multiboot2: Clarify meaning of information request header tag X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bf9199d49be09bda6c0b585d41e65055a4d20ac4;p=thirdparty%2Fgrub.git multiboot2: Clarify meaning of information request header tag Signed-off-by: Daniel Kiper Reviewed-by: Konrad Rzeszutek Wilk --- diff --git a/doc/multiboot.texi b/doc/multiboot.texi index 42430ca8d..ff8c2bb8a 100644 --- a/doc/multiboot.texi +++ b/doc/multiboot.texi @@ -437,15 +437,19 @@ 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 - -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. +@samp{mbi_tag_types} is an array of u32's, each one representing an information request. + +If this tag is present and @samp{optional} is set to @samp{0}, the bootloader must +support the requested tag and be able to provide relevant information to the image +if it is available. If the bootloader does not understand the meaning of the requested +tag it must fail with an error. However, if it supports a given tag but the information +conveyed by it is not available the bootloader does not provide the requested tag in +the Multiboot2 information structure and passes control to the loaded image as usual. + +Note: The above means that there is no 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 the bootloader supports it, no tags of type @samp{8} will be present in the Multiboot2 +information structure. @node Address header tag