Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 15 Nov 2023 08:58:30 +0800 | From | Baoquan He <> | Subject | Re: [PATCH 1/7] kexec_file: add kexec_file flag to control debug printing |
| |
On 11/14/23 at 08:03am, Joe Perches wrote: > On Tue, 2023-11-14 at 23:32 +0800, Baoquan He wrote: > > When specifying 'kexec -c -d', kexec_load interface will print loading > > information, e.g the regions where kernel/initrd/purgatory/cmdline > > are put, the memmap passed to 2nd kernel taken as system RAM ranges, > > and printing all contents of struct kexec_segment, etc. These are > > very helpful for analyzing or positioning what's happening when > > kexec/kdump itself failed. The debugging printing for kexec_load > > interface is made in user space utility kexec-tools. > > > > Whereas, with kexec_file_load interface, 'kexec -s -d' print nothing. > > Because kexec_file code is mostly implemented in kernel space, and the > > debugging printing functionality is missed. It's not convenient when > > debugging kexec/kdump loading and jumping with kexec_file_load > > interface. > > > > Now add KEXEC_FILE_DEBUG to kexec_file flag to control the debugging > > message printing. And add global variable kexec_file_dbg_print and > > macro kexec_dprintk() to facilitate the printing. > > > > This is a preparation, later kexec_dprintk() will be used to replace the > > existing pr_debug(). Once 'kexec -s -d' is specified, it will print out > > kexec/kdump loading information. If '-d' is not specified, it regresses > > to pr_debug(). > > Not quite as pr_debug is completely eliminated with > zero object size when DEBUG is not #defined. > > Now the object size will be larger and contain the > formats in .text.
Ah, I didn't realize that. Thanks for telling. I didn't take pr_info() and pr_debug because I want to avoid printing the pr_fmt() string in each file.
> > [] > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > [] > > @@ -264,6 +264,18 @@ arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section, > > return -ENOEXEC; > > } > > #endif > > + > > +extern bool kexec_file_dbg_print; > > + > > +#define kexec_dprintk(fmt, args...) \ > > + do { \ > > + if (kexec_file_dbg_print) \ > > + printk(KERN_INFO fmt, ##args); \ > > + else \ > > + printk(KERN_DEBUG fmt, ##args); \ > > + } while (0) > > + > > + > > I don't know how many of these printks exist and if > overall object size matters but using
Not too much because they are spread in different arch. > > #define kexec_dprintkfmt, ...) \ > printk("%s" fmt, \ > kexec_file_dbg_print ? KERN_INFO : KERN_DEBUG, \ > ##__VA_ARGS__) > > should reduce overall object size by eliminating the > mostly duplicated format in .text which differs only > by the KERN_<PREFIX>
Sure, the new one looks great to me, I will update code to take it. Thanks a lot for your great suggestion.
Thanks Baoquan
| ![\](/images/icornerr.gif) |