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From: Markus Armbruster <armbru@redhat.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: qemu-devel@nongnu.org, kwolf@redhat.com, qemu-block@nongnu.org,
	alex.bennee@linaro.org, mreitz@redhat.com, qemu-ppc@nongnu.org,
	lersek@redhat.com
Subject: Re: [Qemu-devel] [PATCH v3 06/14] sam460ex: Don't size flash memory to match backing image
Date: Fri, 08 Mar 2019 15:27:05 +0100	[thread overview]
Message-ID: <87wol9bfwm.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <a8a862f1-1f1e-818a-2ac6-bd54375c4dc3@redhat.com> ("Philippe =?utf-8?Q?Mathieu-Daud=C3=A9=22's?= message of "Fri, 8 Mar 2019 15:04:28 +0100")

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> On 3/7/19 2:03 PM, Markus Armbruster wrote:
>> Machine "sam460ex" maps its flash memory at address 0xFFF00000.  When
>> no image is supplied, its size is 1MiB (0x100000), and 512KiB of ROM
>> get mapped on top of its second half.  Else, it's the size of the
>> image rounded up to the next multiple of 64KiB.
>> 
>> The rounding is actually useless: pflash_cfi01_realize() fails with
>> "failed to read the initial flash content" unless it's a no-op.
>> 
>> I have no idea what happens when the pflash's size exceeds 1MiB.
>> Useful outcomes seem unlikely.
>
> You now have! [*] "Hardwiring address lines leaves part of the hardware
> unaddressable." Anything bigger than 1MiB mapped at 0xFFF00000 only has
> the first MiB addressable. IOW anything above 1MiB is unaddressable, but
> you still can map a such bigger flash.
>
> [*] https://lists.gnu.org/archive/html/qemu-devel/2019-03/msg01380.html

Well, that's what would happen with real hardware.  But this device
model doesn't actually model address lines.  It simply asks
pflash_cfi01_register() to map blk_getlength() bytes at the base
address.  If you ask it to map gigabytes, it'll happily do so (as long
as malloc plays along).

  reply	other threads:[~2019-03-08 14:27 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-07 13:03 [Qemu-devel] [PATCH v3 00/14] pflash: Fixes and cleanups Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 01/14] pflash: Rename pflash_t to PFlashCFI01, PFlashCFI02 Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 02/14] pflash_cfi01: Do not exit() on guest aborting "write to buffer" Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 03/14] pflash_cfi01: Log use of flawed " Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 04/14] pflash: Rename *CFI_PFLASH* to *PFLASH_CFI* Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 05/14] hw: Use PFLASH_CFI0{1, 2} and TYPE_PFLASH_CFI0{1, 2} Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 06/14] sam460ex: Don't size flash memory to match backing image Markus Armbruster
2019-03-08 14:04   ` Philippe Mathieu-Daudé
2019-03-08 14:27     ` Markus Armbruster [this message]
2019-03-08 14:34       ` Philippe Mathieu-Daudé
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 07/14] ppc405_boards: " Markus Armbruster
2019-03-08  0:10   ` David Gibson
2019-03-08  7:24     ` Markus Armbruster
2019-03-08 11:09       ` David Gibson
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 08/14] r2d: Fix flash memory size, sector size, width, device ID Markus Armbruster
2019-03-07 13:51   ` Philippe Mathieu-Daudé
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 09/14] hw/mips/malta: Fix the DEBUG_BOARD_INIT code Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 10/14] hw/mips/malta: Remove fl_sectors variable Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 11/14] hw/mips/malta: Restrict 'bios_size' variable scope Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 12/14] mips_malta: Clean up definition of flash memory size somewhat Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 13/14] pflash: Clean up after commit 368a354f02b, part 1 Markus Armbruster
2019-03-07 13:03 ` [Qemu-devel] [PATCH v3 14/14] pflash: Clean up after commit 368a354f02b, part 2 Markus Armbruster
2019-03-08 14:05   ` Philippe Mathieu-Daudé
2019-03-09 13:27 ` [Qemu-devel] [PATCH v3 00/14] pflash: Fixes and cleanups no-reply

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