From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx4-phx2.redhat.com ([209.132.183.25]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VN0OO-0001Y4-J1 for kexec@lists.infradead.org; Fri, 20 Sep 2013 13:05:05 +0000 Date: Fri, 20 Sep 2013 09:04:40 -0400 (EDT) From: Dave Anderson Message-ID: <408026044.15752698.1379682280786.JavaMail.root@redhat.com> In-Reply-To: <523BCD38.4020702@mxc.nes.nec.co.jp> References: <1099586971.12086400.1378996512279.JavaMail.root@redhat.com> <523BCD38.4020702@mxc.nes.nec.co.jp> Subject: Re: [PATCH / RFC] makedumpfile header to show LZO/snappy/zlib MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Atsushi Kumagai Cc: kexec@lists.infradead.org ----- Original Message ----- > Hello Dave, > > (2013/09/16 0:56), Dave Anderson wrote: > > > > With the advent of LZO and snappy compression support, it would be > > helpful if it could be readily determined which type of compression > > was used to create the dumpfile. > > > > The zlib/LZO/snappy indicator is only found down in the bowels of each > > page_desc structure: > > > > /* page flags */ > > #define DUMP_DH_COMPRESSED_ZLIB 0x1 /* page is compressed with zlib > > */ > > #define DUMP_DH_COMPRESSED_LZO 0x2 /* paged is compressed with lzo > > */ > > #define DUMP_DH_COMPRESSED_SNAPPY 0x4 > > /* paged is compressed with > > snappy */ > > > > /* descriptor of each page for vmcore */ > > typedef struct page_desc { > > off_t offset; /* the offset of the > > page data*/ > > unsigned int size; /* the size of this dump > > page */ > > unsigned int flags; /* flags */ > > unsigned long long page_flags; /* page flags */ > > } page_desc_t; > > > > The compressed kdump's header does contain a "status" flag: > > > > struct disk_dump_header { > > char signature[SIG_LEN]; /* = "KDUMP " > > */ > > int header_version; /* Dump header version > > */ > > struct new_utsname utsname; /* copy of > > system_utsname */ > > struct timeval timestamp; /* Time stamp */ > > unsigned int status; /* Above flags */ > > ... > > > > which has these 3 flags: > > > > #define DUMP_HEADER_COMPLETED 0 > > #define DUMP_HEADER_INCOMPLETED 1 > > #define DUMP_HEADER_COMPRESSED 8 > > > > But they are all remnants of the old "diskdump" facility, and none of them > > are ever used by makedumpfile. > > > > Any chance that the LZO/snappy/zlib method could also be put up in > > the disk_dump_header? > > > > Dave > > > > --- makedumpfile-1.5.4/makedumpfile.c.orig > > +++ makedumpfile-1.5.4/makedumpfile.c > > @@ -5162,6 +5162,16 @@ write_kdump_header(void) > > dh->bitmap_blocks = divideup(info->len_bitmap, dh->block_size); > > memcpy(&dh->timestamp, &info->timestamp, sizeof(dh->timestamp)); > > memcpy(&dh->utsname, &info->system_utsname, sizeof(dh->utsname)); > > + if (info->flag_compress & DUMP_DH_COMPRESSED_ZLIB) > > + dh->status |= DUMP_DH_COMPRESSED_ZLIB; > > +#ifdef USELZO > > + else if (info->flag_compress & DUMP_DH_COMPRESSED_LZO) > > + dh->status |= DUMP_DH_COMPRESSED_LZO) > > +#endif > > +#ifdef USESNAPPY > > + else if (info->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) > > + dh->status |= DUMP_DH_COMPRESSED_SNAPPY) > > +#endif > > dh->status will not guarantee that *all pages* are compressed > by the check below: > > > #ifdef USELZO > > } else if (info->flag_lzo_support > > && (info->flag_compress & > > DUMP_DH_COMPRESSED_LZO) > > && ((size_out = info->page_size), > > lzo1x_1_compress(buf, info->page_size, > > buf_out, > > &size_out, wrkmem) == > > LZO_E_OK) > > && (size_out < info->page_size)) { > ^^^^^^^^^^^^^^^^^^^^^^^^^^^ > When there is no effect of compression, the page will not be compressed. > > > pd.flags = DUMP_DH_COMPRESSED_LZO; > > pd.size = size_out; > > memcpy(buf, buf_out, pd.size); > > #endif > > If we are on the same page, I'll accept your patch. Right, I understand. Thanks, Dave > > > Thanks > Atsushi Kumagai > > > > > size = sizeof(struct disk_dump_header); > > if (!write_buffer(info->fd_dumpfile, 0, dh, size, > > info->name_dumpfile)) > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec