Messages in this thread | | | Date | Tue, 20 Nov 2012 16:28:18 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH v2 03/13] x86: Add macro for 64bit entry startup_64 |
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On 11/20/2012 04:20 PM, Yinghai Lu wrote: > > So will have > Bit 1 (read): LOADED_ABOVE_4G > - If 1, code, boot_param, cmdline, ramdisk could be loaded above 4G, > > will update the patches accordingly. >
No, read the below.
>> >> On the other hand, the read flags in loadflags has not been modified for a >> very long time, and there is a serious risk that some broken bootloader >> might be doing a full byte comparison. >> >> relocatable_kernel really should have been a flag, but it is now defined as >> a comparison with zero. As such, and in an effort to minimize the growth of >> struct setup_header (it is limited to little over 128 bytes long) I suggest >> we redefine the 16-byte field at offset 0x236 as a new flags field. We >> still only need one flag, though. >> >> Backwards compatibility is so much fun. > > yes. try to make it ready for future is fun too. > > are you going to have pointer for ext_header ? >
No, it doesn't help us much.
Overall, we need to keep growth of struct setup_header under some control. The highest usable offset is 0x280.
-hpa
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