From: H. Peter Anvin Date: Fri, 22 Feb 2008 03:32:59 +0000 (-0800) Subject: Document intent at no longer providing file length a priori X-Git-Tag: syslinux-3.70-pre1~17 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7c028ed3b4fb62d42fad88c36ea86d904ceee86d;p=profile%2Fivi%2Fsyslinux.git Document intent at no longer providing file length a priori We intend to no longer guarantee that we know the file size ahead of time. --- diff --git a/doc/comboot.doc b/doc/comboot.doc index 46afc64..c4e303a 100644 --- a/doc/comboot.doc +++ b/doc/comboot.doc @@ -293,7 +293,7 @@ AX=0006h [2.08] Open file Input: AX 0006h ES:SI null-terminated filename Output: SI file handle - EAX length of file in bytes + EAX length of file in bytes, or -1 CX file block size Open a file for reading. The exact syntax of the filenames @@ -304,6 +304,9 @@ AX=0006h [2.08] Open file Note: SYSLINUX considers a zero-length file to be nonexistent. + In 3.70 or later, EAX can contain -1 indicating that the file + length is unknown. + AX=0007h [2.08] Read file @@ -312,6 +315,7 @@ AX=0007h [2.08] Read file ES:BX buffer CX number of blocks to read Output: SI file handle, or 0 if EOF was reached + EAX number of bytes read [3.70] Read blocks from a file. Note that the file handle that is returned in SI may not be the same value that was passed in. @@ -319,6 +323,10 @@ AX=0007h [2.08] Read file If end of file was reached (SI=0), the file was automatically closed. + In 3.70 or later, EAX returns the number of bytes read. This + will always be a multiple of the block size unless EOF is + reached. + The address of the buffer (ES:BX) should be at least 512-byte aligned. SYSLINUX guarantees at least this alignment for the COMBOOT load segment or the COM32 bounce buffer.