Date: Thu, 21 Aug 2008 18:37:27 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-hackers@FreeBSD.ORG Subject: Boot loader + malloc Message-ID: <200808211637.m7LGbRhJ008358@lurza.secnetix.de>
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Hello, I've got a small question regarding $subject. I'm looking at this code snippet from src/sys/boot/i386/loader/main.c: #if defined(LOADER_BZIP2_SUPPORT) || defined(LOADER_FIREWIRE_SUPPORT) heap_top = PTOV(memtop_copyin); memtop_copyin -= 0x300000; heap_bottom = PTOV(memtop_copyin); #else heap_top = (void *)bios_basemem; heap_bottom = (void *)end; #endif setheap(heap_bottom, heap_top); If I understand correctly, the boot loader will use only low memory (i.e. below 0x100000) for malloc by default. Extended memory is only used if bzip2 or firewire support are enabled (not default). Is this intentional? Would it make sense to toggle the default and always use extended memory, unless disabled? I'm asking because the upcoming graphics support requires a little bit of memory for fonts and images, but there's only less than about 80 KB left in low memory, which is insufficient except for very trivial things. The loader kept crashing on me in nasty ways because of that. In my p4 branch I modified the above #if to also use extended memory if LOADER_GRAPHICS_SUPPORT is defined, giving me 3 MB of memory to play with, which is plenty. Is that OK, or should I expect trouble? Any comments are appreciated. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "One of the main causes of the fall of the Roman Empire was that, lacking zero, they had no way to indicate successful termination of their C programs." -- Robert Firth
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