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7191b61575
We have a bunch of CONFIG_PPC_EARLY_DEBUG_* options that are intended for bringup/debug only. They hard wire a machine specific udbg backend very early on (before we even probe the platform), and use whatever tricks are available on each machine/cpu to be able to get some kind of output out there early on. So far, on powermac with no serial ports, we have CONFIG_PPC_EARLY_DEBUG_BOOTX to use the low-level btext engine on the screen, but it doesn't do much, at least on 64-bit. It only really gets enabled after the platform has been probed and the MMU enabled. This adds a way to enable it much earlier. From prom_init.c (while still running with Open Firmware), we grab the screen details and set things up using the physical address of the frame buffer. Then btext itself uses the "rm_ci" feature of the 970 processor (Real Mode Cache Inhibited) to access it while in real mode. We need to do a little bit of reorg of the btext code to inline things better, in order to limit how much we touch memory while in this mode as the consequences might be ... interesting. This successfully allowed me to debug problems early on with the G5 (related to gold being broken vs. ppc64 kernels). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
82 lines
2.1 KiB
Bash
82 lines
2.1 KiB
Bash
#!/bin/sh
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#
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# Copyright © 2008 IBM Corporation
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version
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# 2 of the License, or (at your option) any later version.
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# This script checks prom_init.o to see what external symbols it
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# is using, if it finds symbols not in the whitelist it returns
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# an error. The point of this is to discourage people from
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# intentionally or accidentally adding new code to prom_init.c
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# which has side effects on other parts of the kernel.
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# If you really need to reference something from prom_init.o add
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# it to the list below:
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WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
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_end enter_prom memcpy memset reloc_offset __secondary_hold
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__secondary_hold_acknowledge __secondary_hold_spinloop __start
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strcmp strcpy strlcpy strlen strncmp strstr logo_linux_clut224
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reloc_got2 kernstart_addr memstart_addr linux_banner _stext
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opal_query_takeover opal_do_takeover opal_enter_rtas opal_secondary_entry
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boot_command_line __prom_init_toc_start __prom_init_toc_end
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btext_setup_display"
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NM="$1"
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OBJ="$2"
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ERROR=0
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for UNDEF in $($NM -u $OBJ | awk '{print $2}')
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do
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# On 64-bit nm gives us the function descriptors, which have
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# a leading . on the name, so strip it off here.
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UNDEF="${UNDEF#.}"
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if [ $KBUILD_VERBOSE ]; then
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if [ $KBUILD_VERBOSE -ne 0 ]; then
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echo "Checking prom_init.o symbol '$UNDEF'"
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fi
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fi
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OK=0
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for WHITE in $WHITELIST
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do
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if [ "$UNDEF" = "$WHITE" ]; then
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OK=1
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break
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fi
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done
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# ignore register save/restore funcitons
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if [ "${UNDEF:0:9}" = "_restgpr_" ]; then
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OK=1
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fi
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if [ "${UNDEF:0:10}" = "_restgpr0_" ]; then
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OK=1
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fi
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if [ "${UNDEF:0:11}" = "_rest32gpr_" ]; then
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OK=1
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fi
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if [ "${UNDEF:0:9}" = "_savegpr_" ]; then
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OK=1
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fi
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if [ "${UNDEF:0:10}" = "_savegpr0_" ]; then
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OK=1
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fi
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if [ "${UNDEF:0:11}" = "_save32gpr_" ]; then
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OK=1
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fi
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if [ $OK -eq 0 ]; then
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ERROR=1
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echo "Error: External symbol '$UNDEF' referenced" \
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"from prom_init.c" >&2
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fi
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done
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exit $ERROR
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