Messages in this thread Patch in this message | | | Date | Mon, 28 Aug 2006 09:41:47 +0300 | From | Alon Bar-Lev <> | Subject | Re: [PATCH] THE LINUX/I386 BOOT PROTOCOL - Breaking the 256 limit (ping) |
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Alon Bar-Lev wrote: > H. Peter Anvin wrote: >> Found the references. This seems to imply that EDD overwrites the >> area used by LILO 22.6.1. LILO 22.6.1 uses the new boot protocol, >> with the full pointer, and seems to obey the spec as far as I can read >> the code. I'm going to try to run it in simulation and observe the >> failure that way. >> >> However, something is still seriously out of joint. The EDD data >> actually overlays the setup code, not the bootsect code, and thus >> there "shouldn't" be any way that this could interfere. My best guess >> at this time is that either the EDD code or LILO uses memory it's not >> supposed to use, and the simulation should hopefully reveal that. >> >> Sorry if I seem snarky on this, but if we can't get to the bottom of >> this we can't ever fix it. >> >> -hpa >> > > I think I've found one problem... But I it should not be the major one. > The EDD code scans the command-line as fixed string. > What about something like the following? > > Best Regards, > Alon Bar-Lev. > > diff -urNp linux-2.6.18-rc4-mm2/arch/i386/boot/edd.S > linux-2.6.18-rc4-mm2.new/arch/i386/boot/edd.S > --- linux-2.6.18-rc4-mm2/arch/i386/boot/edd.S 2006-06-18 > 04:49:35.000000000 +0300 > +++ linux-2.6.18-rc4-mm2.new/arch/i386/boot/edd.S 2006-08-28 > 08:55:01.000000000 +0300 > @@ -29,6 +29,8 @@ > movl $(COMMAND_LINE_SIZE-7), %ecx > # loop through kernel command line one byte at a time > cl_loop: > + cmpb $0,(%si) > + jz done_cl > cmpl $EDD_CL_EQUALS, (%si) > jz found_edd_equals > incl %esi >
Better patch. I've noticed that this code sets esi but then reference using si... So fixed to use esi (It worked so far since we are in low area... But I think using the same register type is cleaner...)
Best Regards, Alon Bar-Lev.
diff -urNp linux-2.6.18-rc4-mm2/arch/i386/boot/edd.S linux-2.6.18-rc4-mm2.new/arch/i386/boot/edd.S --- linux-2.6.18-rc4-mm2/arch/i386/boot/edd.S 2006-06-18 04:49:35.000000000 +0300 +++ linux-2.6.18-rc4-mm2.new/arch/i386/boot/edd.S 2006-08-28 09:34:39.000000000 +0300 @@ -29,7 +29,9 @@ movl $(COMMAND_LINE_SIZE-7), %ecx # loop through kernel command line one byte at a time cl_loop: - cmpl $EDD_CL_EQUALS, (%si) + cmpb $0,(%esi) + jz done_cl + cmpl $EDD_CL_EQUALS, (%esi) jz found_edd_equals incl %esi loop cl_loop @@ -37,9 +39,9 @@ cl_loop: found_edd_equals: # only looking at first two characters after equals addl $4, %esi - cmpw $EDD_CL_OFF, (%si) # edd=of + cmpw $EDD_CL_OFF, (%esi) # edd=of jz do_edd_off - cmpw $EDD_CL_SKIP, (%si) # edd=sk + cmpw $EDD_CL_SKIP, (%esi) # edd=sk jz do_edd_skipmbr jmp done_cl do_edd_skipmbr: - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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