Re: DOSEMU fails on start with SIGSEGV...

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It looks like gcc-12+ has problems with static const declarations for lowmem_base and mem_base, especcially as they get defined later,  so
I've erased "const" in both definitions ( and extern declarations) and now it works, or at least so it seems.

> ----------------------------------------
> From: Zeni Junker <zeni.junker445@xxxxxxxxxxxxx>
> Date: Jul 30, 2023, 12:41:16 PM
> To: <linux-msdos@xxxxxxxxxxxxxxx>
> Subject: DOSEMU fails on start with SIGSEGV...
> I'm running Gentoo ( if that matters)
> I've tried with version 1.4.0 and latest from git repo and the result is the same.
> Also, it fails the same way whether I start it as a root or ordinary user ( I've added lines for both in dosemu.usrs file: "username/root c_all" ).
> So I've compiled it with "debug" option tried to debug it with gdb.
> Well, this has lead me through the initialization.
> Thing is in main() (in emu.c - line 394) low_mem_init getc called and it fails.
> Peeking within it shows that low_mem_init ( init.c) calls alloc_mapping ( line  261), which fails.
> Peek into alloc_mapping ( file mapping.c) fails in line 419,, when it tries to copy pointer to allocated area to lowmem_base, which is 0 at that point:
> line 419: " *(char **)(&lowmem_base) = addr; "
> Since low memory has never been allocated at that point, this causes SIGSEGV.
> At some point I thought this might be due to some kernel protection etc. Setting in/proc/sys/vm/mmap_min_addr was 65536, so I've reset it to 0 and retried, with the same result.
> Then I've noticed that lowmem_base gets declared as "char * const lowmem_base" in mapping.c and nothing ever sets it, so it is always 0.
> Just to doublecheck, I've inspected /proc/proc_id/maps of debugged process and indeed there was nothing mapped at address 0 - all I've seen are high address map areas that one usually gets from mmap
> in the range 0x7Fxxxxxxxx for various libs etc and 4 mappings of dosemu.bin, also at high adresses.
> But nothing low, so naturally any acess outside of mapped areas SIGSEGVs.
> So, my question is, am I missing something ?
> Shouldn't lowmem_base be set somewhere ?
> If not, shouldn't the low area be mapped in somewhere before that ?
> TIA,
> Zeni
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