From: Rebecca Cran <rebecca@bluestop.org>
To: Andrew Fish <afish@apple.com>, Laszlo Ersek <lersek@redhat.com>
Cc: Mike Kinney <michael.d.kinney@intel.com>,
edk2-devel-01 <edk2-devel@lists.01.org>,
"Gao, Liming" <liming.gao@intel.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: "practical" memory allocation limit?
Date: Mon, 28 Aug 2017 17:53:23 -0600 [thread overview]
Message-ID: <890e9eaf-8c68-4b52-dbba-9938c0315732@bluestop.org> (raw)
In-Reply-To: <E37645E4-1885-43C7-AAB1-F30A21CDE304@apple.com>
On 08/28/2017 10:23 AM, Andrew Fish wrote:
> For X64 (x86-64) systems it is common for PEI to run in 32-bit mode with paging disabled. This means the DXE Core gets loaded under 4GB and and the HOBs and such are < 4GB. So having the initial memory map < 4GB helps with preventing fragmentation.
This is something I ran into with a driver I was working on: when being
Load'd from a PCIe optrom only 4GB RAM could be seen; later, in the
Start function, all 32GB or however much could be accessed.
Then there was still the problem of certain machines limiting
AllocatePool calls to 4GB, which since our driver at times needed many
times that amount required us to iterate over the memory map and call
AllocatePages.
--
Rebecca Cran
prev parent reply other threads:[~2017-08-28 23:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-28 8:43 "practical" memory allocation limit? Laszlo Ersek
2017-08-28 14:25 ` Shi, Steven
2017-08-28 14:39 ` Laszlo Ersek
2017-08-28 15:31 ` Shi, Steven
2017-08-28 16:23 ` Andrew Fish
2017-08-28 17:36 ` Laszlo Ersek
2017-08-28 23:53 ` Rebecca Cran [this message]
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