Date: Thu, 30 Jul 1998 18:26:41 -0400 (EDT) From: "Ron G. Minnich" <rminnich@Sarnoff.COM> To: hackers@FreeBSD.ORG Subject: freebsd mmap: does the offset have to be blocksize-aligned Message-ID: <Pine.SUN.3.91.980730182025.20178A-100000@terra>
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here's a cute one from linux: (generic_file_mmap)
if (vma->vm_offset & (inode->i_sb->s_blocksize - 1))
return -EINVAL;
This is all 2.0.x kernels I have seen. It means that the offset for an
mmap has to be file-system-block-aligned. There are cases where the linux
ld.so double-maps libc.so, and in one case maps part of it on an 8k
boundary. If you have a file system (such as mine) which can support
16384 or larger (65536? sure) blocksizes, elf programs can't run due to
this kernel restriction. Doesn't hurt, e.g., statically linked a.out, as
weird mmaps don't happen for them. Easy to work around, map your /lib with
4k blocks, problem solved, but funny.
any block-aligned restrictions like this in freebsd mmap? I can't think of
having seen it, but you here know better than me. I'm curious.
thanks
ron
Ron Minnich |"Using Windows NT, which is known to have some
rminnich@sarnoff.com | failure modes, on a warship is similar to hoping
(609)-734-3120 | that luck will be in our favor"- A. Digiorgio
ftp://ftp.sarnoff.com/pub/mnfs/www/docs/cluster.html
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