On 19 September 2016 at 01:24, Marc-André Lureau <[email protected]> wrote: > tests/tcg/mmap test fails with values other than default target page > size. When creating a map beyond EOF, extra anonymous pages are added up > to the target page boundary. Currently, this operation is performed only > when qemu_real_host_page_size < TARGET_PAGE_SIZE, but it should be > performed if the configured page size (qemu -p) is larger than > qemu_real_host_page_size too.
What is the purpose of the -p option, does anybody know? I don't see why you'd want to be able to manually set what QEMU thinks the host page size is, it seems like it would mostly only break things. > (also fixes some style issues to please checkpatch) > > Signed-off-by: Marc-André Lureau <[email protected]> > --- > linux-user/mmap.c | 27 ++++++++++++++------------- > 1 file changed, 14 insertions(+), 13 deletions(-) > > diff --git a/linux-user/mmap.c b/linux-user/mmap.c > index c4371d9..4bf79b5 100644 > --- a/linux-user/mmap.c > +++ b/linux-user/mmap.c > @@ -415,31 +415,32 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, > int prot, > } > > /* When mapping files into a memory area larger than the file, accesses > - to pages beyond the file size will cause a SIGBUS. > + to pages beyond the file size will cause a SIGBUS. > > For example, if mmaping a file of 100 bytes on a host with 4K pages > emulating a target with 8K pages, the target expects to be able to > access the first 8K. But the host will trap us on any access beyond > - 4K. > + 4K. > > When emulating a target with a larger page-size than the hosts, we > may need to truncate file maps at EOF and add extra anonymous pages > up to the targets page boundary. */ This comment states what this code is trying to do (handle the case where the target page size is larger than the host page size)... > - if ((qemu_real_host_page_size < TARGET_PAGE_SIZE) > - && !(flags & MAP_ANONYMOUS)) { > - struct stat sb; > + if ((qemu_real_host_page_size < qemu_host_page_size) && > + !(flags & MAP_ANONYMOUS)) { ...but this changes the code so it is no longer doing that. > + struct stat sb; > > - if (fstat (fd, &sb) == -1) > - goto fail; > + if (fstat(fd, &sb) == -1) { > + goto fail; > + } > > /* Are we trying to create a map beyond EOF?. */ > - if (offset + len > sb.st_size) { > - /* If so, truncate the file map at eof aligned with > - the hosts real pagesize. Additional anonymous maps > - will be created beyond EOF. */ > - len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); > - } > + if (offset + len > sb.st_size) { > + /* If so, truncate the file map at eof aligned with > + the hosts real pagesize. Additional anonymous maps > + will be created beyond EOF. */ > + len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); > + } > } > > if (!(flags & MAP_FIXED)) { > -- > 2.10.0 thanks -- PMM
