linux-kernel - Re: [PATCH v4 7/7] ACPI / x86: introduce acpi_os

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Message-ID: <CALCETrVcYbqNpVi4J_iQL1WPYCA1zPJAs+csx73CaQvYziDY1g@mail.gmail.com>
Date:	Tue, 22 Dec 2015 14:49:11 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	"Chen, Yu C" <yu.c.chen@...el.com>
Cc:	"Zheng, Lv" <lv.zheng@...el.com>,
	"Moore, Robert" <robert.moore@...el.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Brown, Len" <len.brown@...el.com>,
	Andy Lutomirski <luto@...nel.org>,
	Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH v4 7/7] ACPI / x86: introduce acpi_os_readable() support

On Mon, Dec 21, 2015 at 5:03 PM, Chen, Yu C <yu.c.chen@...el.com> wrote:
> Hi Andy,
> thanks for your review,
>
>> -----Original Message-----
>> From: Andy Lutomirski [mailto:luto@...capital.net]
>> Sent: Friday, December 18, 2015 1:00 AM
>> To: Zheng, Lv
>> Cc: Chen, Yu C; Moore, Robert; Wysocki, Rafael J; Brown, Len; Andy
>> Lutomirski; Lv Zheng; linux-kernel@...r.kernel.org; Linux ACPI; H. Peter
>> Anvin; Borislav Petkov
>> Subject: Re: [PATCH v4 7/7] ACPI / x86: introduce acpi_os_readable() support
>>
> [cut]
>>
>> I think that hpa or Borislav [cc'd] could address the memory map details
>> better than I could.  However, this functionality seems strange.
>>
>> Are these physical addresses or virtual addresses that are being dumped?
> [Yu] They are  virtual addresses to be dumped.
>> In  either case, ISTM that using something iike page_is_ram might be a lot
>> simpler.
> [Yu] if i understand correctly, this API is used to check if the address is a valid
> 'kmalloc' style address, but not 'kmap' or 'vmalloc' address, and page_is_ram
> might treat the latter as valid address?
>

I'm a bit puzzled as to why this matters, but I have no fundamental
objection to doing it that way.

What's the use case, though?  That is, what goes wrong if the function
just always returns false?

--Andy

> thanks,
> Yu



-- 
Andy Lutomirski
AMA Capital Management, LLC
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