Hi,Dave
As per your suggestion, I updated the patch,and compiled successfully on arm64,
x86,ppc64 architecture
From: Dave Anderson
Sent: Friday, April 3, 2020 0:16
To: 赵乾利
Cc: d hatayama; Discussion list for crash utility usage, maintenance and
development
Subject: Re: 答复: [External Mail]Re: [Crash-utility] zram decompress support for
gcore/crash-utility
- Original Message -
> Hi,Dave & hatayama
>
> I made two patchs in crash-utility and gcore to support zram decompress
> 1.In crash-utility,I add patch in readmem to support zram decompression,
> readmem interface automatically recognizes and decompresses zram data.
> There are some limitations to zram support,only support lzo decompress,kernel
> support lzo,lz4,lz4hc,842,zstd,but lzo is default.
>
> use "rd" command also read data even if mapping to zram
> [without patch]
> crash> rd 144fc000 2
> rd: invalid user virtual address: 144fc000 type: "64-bit UVADDR"
> [with patch]
> crash> rd 144fc000 2
> 144fc000: 06ecdc6b06ecb280 06f027f906eebebe k'..
With respect to the crash utility patch:
Apparently you wrote this patch to only support ARM64? Here's what happens on
an x86_64:
$ patch -p1 < $bos/0001-support-zram-decompress-in-readmem.patch
patching file defs.h
Hunk #5 succeeded at 5304 (offset 2 lines).
patching file memory.c
$ make warn
... [ cut ] ...
cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_7_6 memory.c -Wall -O2
-Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security
In file included from memory.c:19:0:
memory.c: In function 'zram_object_addr':
defs.h:5310:27: error: 'PHYS_MASK_SHIFT' undeclared (first use in this
function)
#define _PFN_BITS(PHYS_MASK_SHIFT - PAGESHIFT())
^
defs.h:5311:43: note: in expansion of macro '_PFN_BITS'
#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
^
memory.c:19838:27: note: in expansion of macro 'OBJ_INDEX_BITS'
page = pfn_to_map(obj >> OBJ_INDEX_BITS);
^
defs.h:5310:27: note: each undeclared identifier is reported only once for
each function it appears in
#define _PFN_BITS(PHYS_MASK_SHIFT - PAGESHIFT())
^
defs.h:5311:43: note: in expansion of macro '_PFN_BITS'
#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
^
memory.c:19838:27: note: in expansion of macro 'OBJ_INDEX_BITS'
page = pfn_to_map(obj >> OBJ_INDEX_BITS);
^
memory.c: In function 'try_zram_decompress':
memory.c:19940:16: error: 'PTE_VALID' undeclared (first use in this function)
if (pte_val & PTE_VALID)
^
memory.c:19932:8: warning: unused variable 'ret' [-Wunused-variable]
ulong ret = 0;
^
make[4]: *** [memory.o] Error 1
make[3]: *** [gdb] Error 2
make[2]: *** [rebuild] Error 2
make[1]: *** [gdb_merge] Error 2
make: *** [warn] Error 2
$
So that's a non-starter. If it can't be made architecture-neutral, then at
least the other major architectures need to be supported. At a minimum all
architectures need to be able to be compiled with LZO enabled.
If you can do that, other suggestions I have for the patch are:
(1) Move all the new offset_table entries to the end of the structure to
prevent
the breakage of previously-compiled extension modules that use OFFSET().
(2) Move the new LZO specific functions to diskdump.c, which is the only C file
that is set up to deal with LZO being #define'd on the fly with "make lzo".
(3) Create a dummy try_zram_decompress() function in diskdump.c that just
returns 0. Put it outside of the LZO function block, e.g.:
#ifdef LZO
zram_object_addr(args... )
...
lookup_swap_cache(args...)
...
try_zram_decompress(args...)
...
#else
try_zram_decompress(args...) { return 0; }
#endif
Alternatively, you could create a try_zram_decompress() macro in defs.h
the same way.
(4) Remove the #ifdef/#endif LZO section of readmem().
(5) PLEASE do not make all the white-space changes in memory.c. It's annoying
to have to review the patch when it's cluttered with changes that are
irrelevant to the task at hand.
Thanks,
Dave
>
> 2.In gcore, I have to make a small change ,change parameter of readmem from
> PHYADDR to UVADDR, other work will be done by crash
>
> Please help review.
> Thanks
>
> -邮件原件-
> 发件人: Dave Anderson
> 发送时间: 2020年4月2日 0:29
> 收件人: 赵乾利
> 抄送: d hatayama ; Discussion list for crash utility
> usage, maintenance and development
> 主题: Re: [External Mail]Re: [Crash-utility] zram decompress support for
> gcore/crash-utility
>
>
>
> - Original Message -
> > Hi,Dave
> > Zram is a virtual device,it simulated as a block device,it's
