Re: [PATCH 12/12] i386 boot: Add an ELF header to bzImage

[Eric W. Biederman]

"H. Peter Anvin" <hpa@xxxxxxxxx> writes:

> Vivek Goyal wrote:
>>>
>> Hi Eric,
>> I have added cld in the regenerated patch below.
>
> No, the cld needs to be earlier.  It turns out this isn't the first use of
> string instructions.

Can we rely on the int calls not setting df?  Otherwise we need to clear
df at each use as we do with all of the later uses.

> I think I am going to add DF=0 as a documented entry condition; it definitely
> seems all current Linux kernels require it.
>
>> Also one more minor nit. stosb relies on being %es set properly. By the
>> time control reaches loader_ok, i could not find %es being set explicitly
>> hence I am assuming we are relying on bootloader to set it up for us. Maybe we
>> can be little more paranoid and setup the %es before stosb. I
>> have done this change too in the attached patch. Pleaese have a look.
>> I know little about assembly code.
>
> %es being set is part of the requirements list, although it *would* be better to
> not rely on any segment registers being set at all (only rely on %cs.)

Agreed.

Eric

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