[U-Boot-Users] U-Boot Memory Allocation for Framebuffer?
wd at denx.de
Tue Jul 27 23:49:22 CEST 2004
In message <31ADFA827355984B9E2A161514595B561C330E at lpdsrv04.logicpd.com> you wrote:
> I'm doing some development on a LCD framebuffer for the OMAP 1510 Innovator
> board (ARM925T CPU), and am encountering some difficulties with code flying
> off to strange places.
> I'm theorizing that the code flies off because memory is not properly
> allocated for the framebuffer. I'm basing all of my new U-Boot related code
> on cpu/mpc8xx/lcd.c, and adding LCD code from the OMAP kernel to get a final
It is not a good idea to use the PPC code as a model as it is based
on a different memory map. It may not work on ARM - on PPC, we
actually compute the relocation address depeding on how much memory
we need to reserve. All this is missing for ARM.
> I'm wondering how the code block above, which also appears in roughly the
> same form in lib_ppc/board.c, is supposed to grab a block of free memory for
> the framebuffer. Do I need to just allocate uchar
It does not gram anything. It is just a copy of PPC code which is
used in a completely different context on PPC.
> framebuffer[col*row*depth+palette] and point the framebuffer address to that
> instead? Something else?
Either you simply make sure not to use the framebuffer area which
follows the BSS segment, or (more complicated) you fix the ARM
implementation and implement real relocation as done for PPC. I'd
prefer to see (2) because this is long overdue, but I could
understand if you chose the simple route.
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de
"Life sucks, but death doesn't put out at all...." - Thomas J. Kopp
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