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| author | H. Peter Anvin <hpa@zytor.com> | 2007-03-30 13:33:47 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2007-03-30 13:33:47 -0700 |
| commit | 48f62dd984768c64a4c481bf41578cb8a0e63c49 (patch) | |
| tree | 6be5aea69b705f04e4a62c1dcba9fc371acdfa55 | |
| parent | 5d85d394d3569191a930cd1dba1d7d68d824a787 (diff) | |
| download | syslinux-elf-syslinux-3.50-pre1.tar.gz syslinux-elf-syslinux-3.50-pre1.tar.xz syslinux-elf-syslinux-3.50-pre1.zip | |
Support chaining shuffle descriptors when buffer is too smallsyslinux-3.50-pre1
Provide a method for re-loading shuffle descriptors from a buffer in
high memory when the shuffle descriptors are too many to fit in the
buffer. This can happen when trying to stitch an initramfs together
from parts. Still need library support for this, however.
| -rw-r--r-- | bcopy32.inc | 21 | ||||
| -rw-r--r-- | comboot.doc | 9 | ||||
| -rw-r--r-- | layout.inc | 2 |
3 files changed, 30 insertions, 2 deletions
diff --git a/bcopy32.inc b/bcopy32.inc index b8e1a5bd..a7b6d6bd 100644 --- a/bcopy32.inc +++ b/bcopy32.inc @@ -442,18 +442,26 @@ try_wbinvd: ; SS register. That is the responsibility of the caller. ; ; Inputs: -; DS:BX -> Pointer to list of (dst, src, len) pairs +; DS:BX -> Pointer to list of (dst, src, len) pairs(*) ; AX -> Number of list entries ; [CS:EntryPoint] -> CS:IP to jump to ; On stack - initial state (fd, ad, ds, es, fs, gs) ; +; (*) If dst == -1, then (src, len) entry refers to a set of new +; descriptors to load. +; If src == -1, then the memory pointed to by (dst, len) is bzeroed; +; this is handled inside the bcopy routine. +; shuffle_and_boot: +.restart: and ax,ax jz .done .loop: mov edi,[bx] mov esi,[bx+4] mov ecx,[bx+8] + cmp edi, -1 + je .reload call bcopy add bx,12 dec ax @@ -468,6 +476,17 @@ shuffle_and_boot: popfd jmp far [cs:EntryPoint] +.reload: + mov bx, trackbuf ; Next descriptor + movzx edi,bx + push ecx ; Save byte count + call bcopy + pop eax ; Byte count + xor edx,edx + mov ecx,12 + div ecx ; Convert to descriptor count + jmp .restart + ; ; trampoline_to_pm: ; diff --git a/comboot.doc b/comboot.doc index 66b8bf2b..f5133e15 100644 --- a/comboot.doc +++ b/comboot.doc @@ -580,6 +580,15 @@ AX=0012h [3.50] Cleanup, shuffle and boot (FFFFFFFFh) then the block specified by the destination address and the length is set to all zero. + Starting in version 3.50, if the destination address is -1 + (FFFFFFFFh) then the data block is loaded as a new set of + descriptors, and processing is continued (and unprocessed + descriptors are lost, this is thus typically only used as the + last descriptor in a block.) The block must still fit in the + internal descriptor buffer (see function 0011h), but can, of + course, itself chain another block. + + Normal boot sectors expect DL to contain the drive number, and, for hard drives (DL >= 80h) DS:SI to contain a pointer to the 16-byte partition table entry. The memory between @@ -26,7 +26,7 @@ TEXT_START equ 7C00h ; The secondary BSS section, above the text; we really wish we could ; just make it follow .bcopy32 or hang off the end, ; but it doesn't seem to work that way. -LATEBSS_START equ 0B200h +LATEBSS_START equ 0B300h ; Reserve memory for the stack. This causes checkov to abort the ; compile if we violate this space. |