| Date | Fri, 22 Nov 2013 07:24:37 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 5/6] kexec-bzImage: Support for loading bzImage using 64bit entry |
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On 11/21/2013 11:21 AM, Vivek Goyal wrote: >> >> What do you mean by the "real mode entry"? Do we need to care about >> that because we aren't falling back to real mode when executing this, >> are we? Or does that just happen for 32bit kernels? > > Original kexec offers real mode entry choice too. So we fall back > to real mode and jump to kernel and kernel makes bunch of BIOS calls. I > don't think this is a commonly used option. >
I know some users of it (who I shall not name.) In general it is a bad option, because after running the first kernel the state of the hardware is not guaranteed to be such that executing the BIOS is safe. In general, I do think they do it just because they tried at some point and it happened to work; discouraging its use is probably for the better.
-hpa
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