linux-kernel - Re: [PATCHv2] x86: EFI stub support for large memory maps

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Date:	Sun, 22 Sep 2013 18:23:28 -0600
From:	Linn Crosetto <linn@...com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	matt.fleming@...el.com, hpa@...or.com, tglx@...utronix.de,
	mingo@...hat.com, x86@...nel.org, yinghai@...nel.org,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2] x86: EFI stub support for large memory maps

On Tue, Sep 17, 2013 at 09:14:52PM +0100, Matt Fleming wrote:
> > +static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
> > +				  u32 *e820ext_size)
> > +{
> > +	efi_status_t status;
> > +	unsigned long size;
> > +
> > +	size = sizeof(struct setup_data) +
> > +		sizeof(struct e820entry) * nr_desc;
> > +
> > +	if (*e820ext && size <= *e820ext_size)
> > +		return EFI_SUCCESS; /* Already allocated */
> 
> Do we actually need this check? I thought the 'prev_nr_desc' below
> ensures we only allocate 'e820ext' if we need more memory.

I am okay with removing the check. There is another bug in exit_boot, when
jumping to get_map the call to get the memory map is passed the previous map
size instead of the size of the allocated buffer. I'll make the changes and
resend.

> 
> [...]
> 
> > @@ -1016,6 +1157,19 @@ get_map:
> >  	if (status != EFI_SUCCESS)
> >  		goto free_mem_map;
> >  
> > +	prev_nr_desc = nr_desc;
> > +	nr_desc = size / desc_size;
> > +	if (nr_desc > prev_nr_desc &&
> > +	    nr_desc > ARRAY_SIZE(boot_params->e820_map)) {
> > +		u32 nr_e820ext = nr_desc - ARRAY_SIZE(boot_params->e820_map);
> > +
> > +		status = alloc_e820ext(nr_e820ext, &e820ext, &e820ext_size);
> > +		if (status != EFI_SUCCESS)
> > +			goto free_mem_map;
> > +
> > +		goto get_map; /* Allocated memory, get map again */
> > +	}
> > +
--
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