Re: memcpy_fromio in dmi_scan.c

From: DuanZhenzhong
Date: Mon Apr 22 2013 - 23:23:58 EST


Jean Delvare wrote:
Hi Duan, Andrew,

I am looking at the following commit:

commit 9f9c9cbb60576a1518d0bf93fb8e499cffccf377
Author: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
Date: Thu Dec 20 15:05:14 2012 -0800

drivers/firmware/dmi_scan.c: fetch dmi version from SMBIOS if it exists

And I am worried about calls to memcpy_fromio(), or lack thereof. Before
this commit, the code would take great care to always call
memcpy_fromio() to get data from the 0xF0000-0xFFFFF memory range (BIOS
data) and operate on that copy. After this commit, the code is happily
calling memcmp() directly on an __iomem pointer. It seems to be harmless
on x86, but it will break on IA64, won't it?

Hi Jean,
What's the impact of reading bios data directly on IA64?
Sorry I have little knowledge about IA64.

zduan
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