Date: Mon, 10 Jan 2022 14:43:13 -0800 From: John Baldwin <jhb@FreeBSD.org> To: Warner Losh <imp@bsdimp.com> Cc: Warner Losh <imp@freebsd.org>, src-committers <src-committers@freebsd.org>, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: d6c0538dae8d - main - ddb: Remove SOFTWARE_SSTEP support Message-ID: <e0aff715-2a17-1d61-ce58-f76eea6c23a4@FreeBSD.org> In-Reply-To: <CANCZdfq0UCZvdcsuaWx3KXqrKBBYoxDHqc=_P3U7L4QpCyh=rw@mail.gmail.com> References: <202201071627.207GRsGX062055@gitrepo.freebsd.org> <45275428-75e2-aaae-bed3-e5e84b39e17c@FreeBSD.org> <CANCZdfq0UCZvdcsuaWx3KXqrKBBYoxDHqc=_P3U7L4QpCyh=rw@mail.gmail.com>
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On 1/10/22 1:14 PM, Warner Losh wrote: > On Mon, Jan 10, 2022 at 12:48 PM John Baldwin <jhb@freebsd.org> wrote: > >> On 1/7/22 8:27 AM, Warner Losh wrote: >>> The branch main has been updated by imp: >>> >>> URL: >> https://cgit.FreeBSD.org/src/commit/?id=d6c0538dae8d138219dfd051994a44c50e741212 >>> >>> commit d6c0538dae8d138219dfd051994a44c50e741212 >>> Author: Warner Losh <imp@FreeBSD.org> >>> AuthorDate: 2022-01-07 16:25:33 +0000 >>> Commit: Warner Losh <imp@FreeBSD.org> >>> CommitDate: 2022-01-07 16:25:33 +0000 >>> >>> ddb: Remove SOFTWARE_SSTEP support >>> >>> It was needed for mips only, and only kinda sorta worked for mips. >> It >>> can be brought back if we grow another architecture that need it. >>> >>> Sponsored by: Netflix >> >> RISC-V would need it in theory (no hardware single step), but no one has >> felt the >> need to implement the backend support for it. I think 32-bit arm doesn't >> support >> hardware single step either (but again, no one has bothered to add the >> backend >> support). >> > > Generally, I agree with these thoughts. I went ahead with the removal > because I > knew it would be easy to bring back, even years from now should someone[tm] > have an implementation for those platforms (though I thought 32-bit arm did > have > single step in hardware). > > Should I put it back? Or should we wait until someone shows up with support > for > a supported platform? I think the latter. I don't know that I've ever used single step in DDB on any platform myself. In my experience, using a gdb stub in QEMU or via JTAG or the like is a much better experience for debugging boot-time initialization. -- John Baldwin
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