linux-kernel - EFI Virtual Address Mapping

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Message-ID: <88e91b480812101542m76f61eecm9d3e4dec2c8b23ea@mail.gmail.com>
Date:	Wed, 10 Dec 2008 18:42:24 -0500
From:	"Jonathan Barkelew" <debtech@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: EFI Virtual Address Mapping - MAX PAGES too low?

I've traced a series of kernel panics on one of my projects back to a
failed call to efi_ioremap in efi_64.c. In my project, there is a 4MB
region in the EFI memory map declared as EFI_MEMORY_RUNTIME, but
efi_ioremap fails if the total number of mapped pages is greater than
100:

if (pages_mapped + pages > MAX_EFI_IO_PAGES)
    return NULL;

A 4MB runtime region seems to be allowed by the EFI spec. Why is
MAX_EFI_IO_PAGES so low?

----
Jonathan Barkelew
debtech@...il.com
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